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Sample records for vibrational ball milling

  1. Regularity and mechanism of wheat straw properties change in ball milling process at cellular scale.

    Science.gov (United States)

    Gao, Chongfeng; Xiao, Weihua; Ji, Guanya; Zhang, Yang; Cao, Yaoyao; Han, Lujia

    2017-10-01

    To investigate the change of structure and physicochemical properties of wheat straw in ball milling process at cellular scale, a series of wheat straws samples with different milling time were produced using an ultrafine vibration ball mill. A multitechnique approach was used to analyze the variation of wheat straw properties. The results showed that the characteristics of wheat straw powder displayed regular changes as a function of the milling time, i.e., the powder underwent the inversion of breakage to agglomerative regime during wheat straw ball milling process. The crystallinity index, bulk density and water retention capacity of wheat straw were exponential relation with ball milling time. Moreover, ball milling continually converted macromolecules of wheat straw cell wall into water-soluble substances resulting in the water extractives proportional to milling time. Copyright © 2017. Published by Elsevier Ltd.

  2. CVD carbon powders modified by ball milling

    Directory of Open Access Journals (Sweden)

    Kazmierczak Tomasz

    2015-09-01

    Full Text Available Carbon powders produced using a plasma assisted chemical vapor deposition (CVD methods are an interesting subject of research. One of the most interesting methods of synthesizing these powders is using radio frequency plasma. This method, originally used in deposition of carbon films containing different sp2/sp3 ratios, also makes possible to produce carbon structures in the form of powder. Results of research related to the mechanical modification of these powders have been presented. The powders were modified using a planetary ball mill with varying parameters, such as milling speed, time, ball/powder mass ratio and additional liquids. Changes in morphology and particle sizes were measured using scanning electron microscopy and dynamic light scattering. Phase composition was analyzed using Raman spectroscopy. The influence of individual parameters on the modification outcome was estimated using statistical method. The research proved that the size of obtained powders is mostly influenced by the milling speed and the amount of balls. Powders tend to form conglomerates sized up to hundreds of micrometers. Additionally, it is possible to obtain nanopowders with the size around 100 nm. Furthermore, application of additional liquid, i.e. water in the process reduces the graphitization of the powder, which takes place during dry milling.

  3. The application of response surface method to optimization of precision ball end milling

    Directory of Open Access Journals (Sweden)

    Wojciechowski Szymon

    2017-01-01

    Full Text Available This paper is focused on the multi criteria optimization of precision ball end milling process of hardened 55NiCrMoV6 steel. The proposed method enables the selection of optimal input parameters which affect the minimization of cutting forces and vibrations signals, as well as the maximization of process efficiency. The experiment includes the measurement of forces and vibrations during the milling tests with variable input parameters. Ultimately, the optimization of the ball end milling process with the application of response surface method is carried out.

  4. Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Li

    2011-05-04

    In this work, wet ball milling method is used in order to improve hydrogen sorption behaviour due to its improved microstructure of solid hydrogen materials. Compared to traditional ball milling method, wet ball milling has benefits on improvement of MgH{sub 2} microstructure and further influences on its hydrogen sorption behavior. With the help of solvent tetrahydrofuran (THF), wet ball milled MgH{sub 2} powder has much smaller particle size and its specific surface area is 7 times as large as that of dry ball milled MgH{sub 2} powder. Although after ball milling the grain size is decreased a lot compared to as-received MgH{sub 2} powder, the grain size of wet ball milled MgH{sub 2} powder is larger than that of dry ball milled MgH{sub 2} powder due to the lubricant effect of solvent THF during wet ball milling. The improved particle size and specific surface area of wet ball milled MgH{sub 2} powder is found to be determining its hydrogen sorption kinetics especially at relatively low temperatures. And it also shows good cycling sorption behavior, which decides on its industrial applicability. With three different catalysts MgH{sub 2} powder shows improved hydrogen sorption behavior as well as the cyclic sorption behavior. Among them, the Nb{sub 2}O{sub 5} catalyst is found to be the most effective one in this work. Compared to the wet ball milled MgH{sub 2} powder, the particle size and specific surface area of the MgH{sub 2} powder with catalysts are similar to the previous ones, while the grain size of the MgH{sub 2} with catalysts is much finer. In this case, two reasons for hydrogen sorption improvement are suggested: one is the reduction of the grain size. The other may be as pointed out in some literatures that formation of new oxidation could enhance the hydrogen sorption kinetics, which is also the reason why its hydrogen capacity is decreased compared to without catalysts. After further ball milling, the specific surface area of wet ball milled Mg

  5. Attempted - to -Phase Conversion of Croconic Acid via Ball Milling

    Science.gov (United States)

    2017-05-18

    process was analyzed to determine the peak pressures and impact durations experienced by the CA powder during milling. Differential scanning...stainless steel ball and vessel. ................ 6 Fig. 6 Representative heat flow traces for milled CA samples. Curves have been offset to enhance...vessel on each swing. A Wig-L-Bug (Dentsply Rinn) ball mill was used to induce high dynamic pressures in as-received CA powder . The Wig-L-Bug is

  6. The study on dynamic properties of monolithic ball end mills with various slenderness

    Science.gov (United States)

    Wojciechowski, Szymon; Tabaszewski, Maciej; Krolczyk, Grzegorz M.; Maruda, Radosław W.

    2017-10-01

    The reliable determination of modal mass, damping and stiffness coefficient (modal parameters) for the particular machine-toolholder-tool system is essential for the accurate estimation of vibrations, stability and thus the machined surface finish formed during the milling process. Therefore, this paper focuses on the analysis of ball end mill's dynamical properties. The tools investigated during this study are monolithic ball end mills with different slenderness values, made of coated cemented carbide. These kinds of tools are very often applied during the precise milling of curvilinear surfaces. The research program included the impulse test carried out for the investigated tools clamped in the hydraulic toolholder. The obtained modal parameters were further applied in the developed tool's instantaneous deflection model, in order to estimate the tool's working part vibrations during precise milling. The application of the proposed dynamics model involved also the determination of instantaneous cutting forces on the basis of the mechanistic approach. The research revealed that ball end mill's slenderness can be considered as an important milling dynamics and machined surface quality indicator.

  7. The study on dynamic properties of monolithic ball end mills with various slenderness

    Directory of Open Access Journals (Sweden)

    Wojciechowski Szymon

    2017-01-01

    Full Text Available The reliable determination of modal mass, damping and stiffness coefficient (modal parameters for the particular machine-toolholder-tool system is essential for the accurate estimation of vibrations, stability and thus the machined surface finish formed during the milling process. Therefore, this paper focuses on the analysis of ball end mill's dynamical properties. The tools investigated during this study are monolithic ball end mills with different slenderness values, made of coated cemented carbide. These kinds of tools are very often applied during the precise milling of curvilinear surfaces. The research program included the impulse test carried out for the investigated tools clamped in the hydraulic toolholder. The obtained modal parameters were further applied in the developed tool's instantaneous deflection model, in order to estimate the tool's working part vibrations during precise milling. The application of the proposed dynamics model involved also the determination of instantaneous cutting forces on the basis of the mechanistic approach. The research revealed that ball end mill's slenderness can be considered as an important milling dynamics and machined surface quality indicator.

  8. Field-ball milling induced anisotropy in magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Poudyal, Narayan [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Altuncevahir, Baki [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chakka, Vamsi [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chen Kanghua [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Black, Truman D [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Liu, J Ping [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Ding, Yong [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wang Zhonglin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2004-12-21

    Nd{sub 2}Fe{sub 14}B and Sm{sub 2}Co{sub 17} particles of submicrometre sizes have been prepared by ball milling in a magnetic field. Structural and magnetic characterization reveal that these submicrometre particles milled in a magnetic field, consisting of nanosize grains, exhibit strong magnetic anisotropy compared with the particles milled without a magnetic field. Based on in situ observations of the field-ball milling in a transparent container, the mechanism of field-induced anisotropy in the nanostructured hard magnetic particles is discussed. (rapid communication)

  9. Ball milling and annealing of Co-50 at% W Powders

    CSIR Research Space (South Africa)

    Bolokang, AS

    2013-04-01

    Full Text Available annealing of unmilled compacts yielded metastable phases. Upon 10 and 20 h ball milling of Co-W powder, no alloying was obtained. Although milling did not yield significant crystal changes in W and Co ground state struc- tures, its effect is evident during...

  10. Structural and magnetic properties of ball milled copper ferrite

    DEFF Research Database (Denmark)

    Goya, G.F.; Rechenberg, H.R.; Jiang, Jianzhong

    1998-01-01

    The structural and magnetic evolution in copper ferrite (CuFe2O4) caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe2O4 to about 6 nm and induces...

  11. Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

    Directory of Open Access Journals (Sweden)

    Zhiliang Chen

    2016-07-01

    Full Text Available Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization of heavy metals in municipal solid waste incineration (MSWI fly ash. Three heavy metals (Cu, Cr, Pb loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a significant decrease in particle size, a rise in its BET-surface, and turning basic crystals therein into amorphous structures. The dissolution rate of acid buffering materials present in activated particles is enhanced, resulting in a rising pH value of the leachate, reducing the leaching out of some heavy metals.

  12. Modeling and Analysis of High-Energy Ball Milling Through Attritors

    Science.gov (United States)

    Zhao, Xuzhe; Shaw, Leon

    2017-09-01

    The effects of major processing parameters of attritor mills on ball milling efficiency ( i.e., minimum energy consumption with maximum milling progress) are investigated using discrete element modeling (DEM). The major processing parameters investigated include the size of balls, ball volume fraction inside the canister, ball milling velocity, and design of the impeller shaft of the attritor mill. Their effects are studied through examination of the output parameters including the average speed of balls, maximum speed of balls, and torque applied on the impeller shaft. The torque on the impeller shaft represents the energy consumption during ball milling, while the difference between the maximum and average speeds of balls scales with the compressive pressure during "mini-forging" of powder particles trapped between the colliding balls and thus scales with milling progress (particle deformation and size reduction). The simulation reveals that the ball milling velocity, ball volume fraction inside the canister, ball size, and impeller shaft design are all important parameters for energy-efficient ball milling. In particular, high ball milling velocities can lead to larger particle deformation and faster size reduction with minimum energy consumption. Further, ball sizes smaller than the gap that will not be hit by impellers directly are good for high-energy-efficient ball milling. Otherwise, energy consumption increases substantially.

  13. Preparation of iron sulphides by high energy ball milling

    DEFF Research Database (Denmark)

    Lin, R.; Jiang, Jianzhong; Larsen, R.K.

    1998-01-01

    The reaction of a powder mixture consisting of 50 a.% Fe and 50 a.% S during high energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. After around 19 h of milling FeS2 and FeS havebeen formed. By further milling the FeS compound becomes dominating and only Fe......S with an average crystallite size of about 10 nm was observed after milling times longer than 67 h. Mossbauer spectra obtained with applied fields show that the particles are antiferromagnetic or have a strongly canted spin structure....

  14. Transformation of Goethite to Hematite Nanocrystallines by High Energy Ball Milling

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    O. M. Lemine

    2014-01-01

    Full Text Available α-Fe2O3 nanocrystallines were prepared by direct transformation via high energy ball milling treatment for α-FeOOH powder. X-ray diffraction, Rietveld analysis, TEM, and vibrating sample magnetometer (VSM are used to characterize the samples obtained after several milling times. Phase identification using Rietveld analysis showed that the goethite is transformed to hematite nanocrystalline after 40 hours of milling. HRTEM confirm that the obtained phase is mostly a single-crystal structure. This result suggested that the mechanochemical reaction is an efficient way to prepare some iron oxides nanocrystallines from raw materials which are abundant in the nature. The mechanism of the formation of hematite is discussed in text.

  15. Modeling on the Effect of Coal Loads on Kinetic Energy of Balls for Ball Mills

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    Yan Bai

    2015-07-01

    Full Text Available This paper presents a solution for the detection and control of coal loads that is more accurate and convenient than those currently used. To date, no research has addressed the use of a grinding medium as the controlled parameter. To improve the accuracy of the coal load detection based on the kinetic energy of balls in a tubular ball mill, a Discrete Element Method (DEM model for ball kinematics based on coal loads is proposed. The operating process for a ball mill and the ball motion, as influenced by the coal quality and the coal load, was analyzed carefully. The relationship between the operating efficiency of a coal pulverizing system, coal loads, and the balls’ kinetic energy was obtained. Origin and Matlab were utilized to draw the variation of parameters with increasing coal loads in the projectile and cascading motion states. The parameters include the balls’ real-time kinetic energy, the friction energy consumption, and the mill’s total work. Meanwhile, a method of balanced adjacent degree and a physical experiment were proposed to verify the considerable effect of the balls’ kinetic energy on coal loads. The model and experiment results indicate that a coal load control method based on the balls’ kinetic energy is therefore feasible for the optimized operation of a coal pulverizing system.

  16. Iron Nanoparticles Fabricated by High-Energy Ball Milling for Magnetic Hyperthermia

    Science.gov (United States)

    Tung, D. K.; Manh, D. H.; Phong, L. T. H.; Nam, P. H.; Nam, D. N. H.; Anh, N. T. N.; Nong, H. T. T.; Phan, M. H.; Phuc, N. X.

    2016-05-01

    Iron nanoparticles (FeNPs) have been successfully prepared by high-energy ball milling in air for various milling times from 1 h to 32 h. Their structure, particle size, elemental composition, magnetic, and inductive heating properties were investigated by means of x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy, energy-dispersive x-ray (EDX) spectroscopy, vibrating-sample magnetometry, and magnetic induction heating, respectively. XRD analysis showed that the average crystallite size decreased to 11 nm after 10 h of milling, then remained almost unchanged for longer milling times. Coexistence of iron (Fe) and iron oxide (FeO) phases was detected after 12 h of milling. EDX analysis also confirmed the occurrence of oxidation, which can be reconciled with the corresponding decrease and increase in saturation magnetization ( M s) with milling time when exposed to oxygen and when annealed under H2 ambient due to oxygen reduction. The time-dependent magnetic and inductive heating responses of the FeNPs were investigated for prospective application in magnetic hyperthermia. The effect of varying the alternating-current (AC) magnetic field strength on the saturation heating temperature and specific loss power of FeNP-containing ferrofluid with concentration of 4 mg/mL was also studied and is discussed.

  17. Effect of Ball Milling Time on Microstructure and Hardness of Porous Magnesium/Carbon Nanofiber Composites

    Science.gov (United States)

    Xu, Huiru; Zou, Ning; Li, Qizhen

    2017-07-01

    Porous magnesium/carbon nanofiber composites were produced using a powder metallurgic method to study the effect of ball milling time on their microstructure and hardness. Three ball milling times (240 min, 320 min, and 480 min) and two carbon nanofiber concentrations (0.05% and 1%) were utilized in the production of these porous composites. The increase of ball milling time led to the gradual decrease of the average size of magnesium powders from the initial 40 µm to about 26 µm after 480 min of ball milling. The powder size range first increased with the increase of ball milling time from 240 min to 320 min, and then decreased with the further increase of ball milling time to 480 min. Among the three ball milling times, the produced porous composites from the powders after 320 min of ball milling have the largest average pore size. With the increase of ball milling time from 240 min to 320 min and then to 480 min, the average Vickers microhardness data first decreased and then increased for Mg-1%C porous composites along the cross-sections parallel to the compact processing direction, increased for the cross-sections perpendicular to the compact processing direction for Mg-1%C porous composites, first increased and then decreased for the cross-sections parallel to the compact processing direction for Mg-0.05%C porous composites, and slightly decreased for the cross-sections perpendicular to the compact processing direction for Mg-0.05%C porous composites.

  18. Microstructure Evolution of Ni-Based ODS Superalloy Powders During Horizontal Rotary Ball Milling

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    Lee H.-E.

    2017-06-01

    Full Text Available Microstructure evolution of Ni-based oxide dispersion-strengthened alloy powders with milling time is investigated. The elemental powders having a nominal composition of Ni-15Cr-4.5Al-4W-2.5Ti-2Mo-2Ta-0.15Zr-1.1Y2O3 in wt % were ball-milled by using horizontal rotary ball milling with the change of milling velocity. Microstructure observation revealed that large aggregates were formed in the early stages of ball milling, and further milling to 5 h decreased particle size. The average crystalline size, estimated by the peak broadening of XRD, decreased from 28 nm to 15 nm with increasing milling time from 1 h to 5 h. SEM and EPMA analysis showed that the main elements of Ni and Cr were homogeneously distributed inside the powders after ball milling of 5 h.

  19. Magnetization and Specific Absorption Rate Studies of Ball-Milled Iron Oxide Nanoparticles for Biomedicine

    Directory of Open Access Journals (Sweden)

    P. Burnham

    2013-01-01

    Full Text Available Comparative studies are presented of iron oxide nanoparticles in the 7–15 nm average diameter range ball milled in hexane in the presence of oleic acid. Transmission electron microscopy identified spherical particles of decreasing size as milling time and/or surfactant concentration increased. Micromagnetic characterization via Mössbauer spectroscopy at room temperature yielded broadened magnetic spectroscopic signatures, while macromagnetic characterization via vibrating sample magnetometry of 7-8 nm diameter particles showed largely superparamagnetic behavior at room temperature and hysteretic at 2 K. Zero-field and field-cooled magnetization curves exhibited a broad maximum at ~215 K indicating the presence of strong interparticle magnetic interactions. The specific absorption rates of ferrofluids based on these nanoparticle preparations were measured in order to test their efficacies as hyperthermia agents.

  20. Rotationally Vibrating Electric-Field Mill

    Science.gov (United States)

    Kirkham, Harold

    2008-01-01

    A proposed instrument for measuring a static electric field would be based partly on a conventional rotating-split-cylinder or rotating-split-sphere electric-field mill. However, the design of the proposed instrument would overcome the difficulty, encountered in conventional rotational field mills, of transferring measurement signals and power via either electrical or fiber-optic rotary couplings that must be aligned and installed in conjunction with rotary bearings. Instead of being made to rotate in one direction at a steady speed as in a conventional rotational field mill, a split-cylinder or split-sphere electrode assembly in the proposed instrument would be set into rotational vibration like that of a metronome. The rotational vibration, synchronized with appropriate rapid electronic switching of electrical connections between electric-current-measuring circuitry and the split-cylinder or split-sphere electrodes, would result in an electrical measurement effect equivalent to that of a conventional rotational field mill. A version of the proposed instrument is described.

  1. The Tool Life of Ball Nose end Mill Depending on the Different Types of Ramping

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    Vopát Tomáš

    2014-12-01

    Full Text Available The article deals with the cutting tool wear measurement process and tool life of ball nose end mill depending on upward ramping and downward ramping. The aim was to determine and compare the wear (tool life of ball nose end mill for different types of copy milling operations, as well as to specify particular steps of the measurement process. In addition, we examined and observed cutter contact areas of ball nose end mill with machined material. For tool life test, DMG DMU 85 monoBLOCK 5-axis CNC milling machine was used. In the experiment, cutting speed, feed rate, axial depth of cut and radial depth of cut were not changed. The cutting tool wear was measured on Zoller Genius 3s universal measuring machine. The results show different tool life of ball nose end mills depending on the copy milling strategy.

  2. The Tool Life of Ball Nose end Mill Depending on the Different Types of Ramping

    Science.gov (United States)

    Vopát, Tomáš; Peterka, Jozef; Kováč, Martin

    2014-12-01

    The article deals with the cutting tool wear measurement process and tool life of ball nose end mill depending on upward ramping and downward ramping. The aim was to determine and compare the wear (tool life) of ball nose end mill for different types of copy milling operations, as well as to specify particular steps of the measurement process. In addition, we examined and observed cutter contact areas of ball nose end mill with machined material. For tool life test, DMG DMU 85 monoBLOCK 5-axis CNC milling machine was used. In the experiment, cutting speed, feed rate, axial depth of cut and radial depth of cut were not changed. The cutting tool wear was measured on Zoller Genius 3s universal measuring machine. The results show different tool life of ball nose end mills depending on the copy milling strategy.

  3. Ammonia synthesis over multi-promoted iron catalysts obtained by high-energy ball-milling

    DEFF Research Database (Denmark)

    Jacobsen, C.J.H.; Jiang, Jianzhong; Mørup, Steen

    1999-01-01

    that high-energy ball-milling offers some interesting possibilities for preparing novel catalytic materials. It is observed that ball-milling of the powder oxides mixture leads to formation of solid solutions and the catalytic activity is significantly higher than that of the starting material. Furthermore...

  4. An analytical model for force prediction in ball nose micro milling of inclined surfaces

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2010-01-01

    Ball nose micro milling is a key process for the generation of free form surfaces and inclined surfaces often present in mould inserts for micro replication. This paper presents a new cutting force model for ball nose micro milling that is capable of taking into account the effect of the edge...... radius and the effect of the surface topography due to the previous milling passes. The model is completely analytical can be applied to ball end micro milling of slanted surfaces for any value of the surface inclination angle relative to the tool axis....

  5. In situ high temperature study of ZrO 2 ball-milled to nanometer sizes

    Science.gov (United States)

    Gajović, A.; Furić, K.; Štefanić, G.; Musić, S.

    2005-06-01

    Nanostructured ZrO 2 was prepared by high-energy ball-milling under different conditions and sintered at high temperatures. Structural and microstructural changes during the ball-milling were monitored using Raman spectroscopy (RS), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The sintering process was monitored in situ at high temperature (300-1400 °C) by RS and XRD. The results of RS showed that the ball-milling had little or no influence on the transition from the starting monoclinic ZrO 2 to the high-temperature tetragonal ZrO 2. It was concluded that a partial transition from monoclinic to tetragonal polymorph, observed in some earlier ball-milling experiments, can be attributed to the stabilizing influence of impurities introduced due to the wearing of the milling media. In the present experiment ZrO 2 ball-milling assembly was used, which reduced the influence of an additional material. The results of the line broadening analysis, performed using Rietveld refinements of the ball-milling products with powder-to-ball weight ratio ( R) 1:10, indicated a decrease in the crystallite size and an increase in the microstrains with an increase in the ball-milling time up to 3 h. Further increase in the ball-milling time up to 10 h had a very small influence on the size and strain of the obtained m-ZrO 2 products. A difference between the results of in situ RS and XRD analysis of the samples subjected to prolonged ball-milling was attributed to the chemical and microstractural differences between the surface and the bulk of the ZrO 2 particles during the sintering at high temperatures.

  6. Actual behaviour of a ball vibration absorber

    Czech Academy of Sciences Publication Activity Database

    Pirner, Miroš

    2002-01-01

    Roč. 90, č. 8 (2002), s. 987-1005 ISSN 0167-6105 R&D Projects: GA ČR(CZ) GV103/96/K034 Institutional support: RVO:68378297 Keywords : TV towers * wind-excited vibrations * vibration absorbers * pendulum absorber Subject RIV: JM - Building Engineering Impact factor: 0.513, year: 2002 http://www.sciencedirect.com/science/article/pii/S0167610502002155#

  7. Effect of milling time on microstructure and properties of Nano-titanium polymer by high-energy ball milling

    Science.gov (United States)

    Wang, Bo; Wei, Shicheng; Wang, Yujiang; Liang, Yi; Guo, Lei; Xue, Junfeng; Pan, Fusheng; Tang, Aitao; Chen, Xianhua; Xu, Binshi

    2018-03-01

    Nano-titanium (Nano-Ti) was prepared by high-energy ball milling from pure Ti power and grinding agents (Epoxy resin) at room temperature. The effect of milling time on structure and properties of Nano-Ti polymer were investigated systematically. The results show that high-energy ball milling is an effective way to produce Nano-Ti polymer. The dispersion stability and compatibility between Ti power and grinding agents are improved by prolonging the milling time at a certain degree, that is to say, the optimization milling time is 240 min. The particle size of Ti powder and the diffraction peaks intensity of Ti decrease obviously as the milling time increases due to the compression stress, shear friction and other mechanical forces are formed during ball milling. FT-IR result displays that the wavenumber of all the bands move to lower wavenumber after ball milling, and the epoxy ring is open. The system internal energy rises owing to the broken epoxy group and much more Nano-Ti is formed to promote the grafting reaction between Nano-Ti and epoxy resin. The results from TEM and XPS also prove that. And the grafting ration is maximum as the milling time is 240 min, the mass loss ratio is 17.53%.

  8. Surface modification of titanium hydride with epoxy resin via microwave-assisted ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Ning, Rong [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Chen, Ding, E-mail: ma97chen@hotmail.com [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Qianxia [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Bian, Zhibing; Dai, Haixiong; Zhang, Chi [Jiangsu Jinling Special Paint Co., Ltd., Yangzhou 225212 (China)

    2014-10-15

    Highlights: • TiH{sub 2} was modified with epoxy resin by microwave-assisted ball milling. • The epoxy ring was opened under the coupling effect of microwave and ball milling. • Microwave-assisted ball milling improved the compatibility of TiH{sub 2} with epoxy. - Abstract: Surface modification of titanium hydride with epoxy resin was carried out via microwave-assisted ball milling and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and Fourier transform infrared spectroscopy (FT-IR). A sedimentation test was performed to investigate the compatibility of the modified nano titanium hydride with the epoxy resin. The results show that the epoxy resin molecules were grafted on the surface of nano titanium hydride particles during the microwave-assisted ball milling process, which led to the improvement of compatibility between the nanoparticles and epoxy resin. According to the FT-IR, the grafting site was likely to be located around the epoxy group due to the fact that the epoxy ring was opened. However, compared with microwave-assisted ball milling, the conventional ball milling could not realize the surface modification, indicating that the coupling effect of mechanical force and microwave played a key role during the process.

  9. Reversible a-Fe2O3 to Fe3O4 transformation during ball milling

    DEFF Research Database (Denmark)

    Linderoth, Søren; Jiang, Jianzhong; Mørup, Steen

    1997-01-01

    The transformation of hematite to magnetite by high-energy ball milling in a sealed container has been studied by Mossbauer spectroscopy and x-ray diffraction. Mechanisms for this transformation are critically discussed. The dominant mechanism is concluded to be due to bond breaking during the high...... energy ball milling followed by release of the oxygen from the vial. The reverse transformation, magnetite to hematite, is demonstrated to occur by ball milling in air. Mechanisms for this reverse transformation are also put forward....

  10. Ferromagnetic behavior of nanocrystalline Cu–Mn alloy prepared by ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, B.N., E-mail: bholanath_mondal@yahoo.co.in [Department of Central Scientific Services, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Sardar, G. [Department of Zoology, Baruipur College, South 24 parganas 743 610 (India); Nath, D.N. [Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Chattopadhyay, P.P. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

    2014-12-15

    50Cu–50Mn (wt%) alloy was produced by ball milling. The milling was continued up to 30 h followed by isothermal annealing over a four interval of temperature from 350 to 650 °C held for 1 h. Crystallite size, lattice strain, lattice parameter were determined by Rietveld refinement structure analysis of X-ray diffraction data. The amount of dissolved/precipitated Mn (wt%) after ball milling/milling followed by annealing was calculated by quantative phase analysis (QPA). The increase of coercivity could be attributed to the introduction of lattice strain and reduction of crystallite size as a function of milling time. Electron paramagnetic resonance and superconducting quantum interface device analysis indicate that soft ferromagnetic behavior has been achieved by ball milled and annealed Cu–Mn alloy. The maximum coercivity value of Cu–Mn alloy obtained after annealing at 350 °C for 1 h is 277 Oe. - Highlights: • A small amount of Mn has dissolved in Cu after ball milling for 30 h. • Coercivity of the Cu–Mn alloy has increased with an increase in milling time. • Substantial MnO has formed after annealing at 650 °C for 1 h. • The ball milled and annealed alloy have revealed soft ferromagnetic behavior. • The alloy annealed at 350 °C shows the maximum value of coercivity.

  11. Effect of high-energy ball milling in the structural and textural properties of kaolinite

    Directory of Open Access Journals (Sweden)

    E. C. Leonel

    2014-06-01

    Full Text Available Through the process of high-energy ball milling it is possible to obtain solid materials with higher surface area and different particle sizes. These characteristics are very important for some application such as adsorption. Besides, applications of some clays depend on the functionalization which, for kaolinite, takes place in the aluminol groups. Modification in the structural and textural properties of kaolinite by high-energy milling can improve functionalization of kaolinite due to the exposure of aluminol groups. In this work studies were done on the influence of high-energy ball milling on the morphological properties of kaolinite, taking into account parameters such as filling of the miller, number of balls and amount of mass to be milled. Moreover, studies involving milling kinetics of purified kaolinite were carried out to verify modification in the morphology of kaolinite with milling time.

  12. The effect of processing parameters on energy consumption of ball mill refiner for chocolate

    Directory of Open Access Journals (Sweden)

    Fišteš Aleksandar Z.

    2013-01-01

    Full Text Available A laboratory ball mill consisting of vertical cylinder, equipped with a rotating shaft with arms, and filled with steel balls as a grinding medium has been used in the experiments. The aim of the study was to examine the effect of agitator shaft speed and amount of grinding media (steel balls on power requirements and energy consumption of a ball mill. With constant mass of the steel balls (20 kg, 30 kg and 40 kg, the agitator shaft speed was increased from 10% to 100% of the maximum speed which corresponds to a speed of 50 rpm. The power consumption (W was recorded upon which milling energy consumption (J/kg has been calculated. The results were statistically analyzed using ANOVA. The increase of the agitator shaft speed, in steps of 10% to the maximum speed of 50 rpm, led to a statistically significant increase in milling energy consumption. At low agitator shaft speed (10%, increase in the mass of the steel balls had no influence on the power requirements. Power requirements for the grinding runs using 30 kg and 40 kg are similar and higher compared to power requirement in trial with 20 kg, as agitator shaft speed increases from 20% to 70%. At high agitator shaft speeds (≥80%, increase in steel balls mass led to the significant increase in power requirements of the ball mill.

  13. Transforming from paramagnetism to room temperature ferromagnetism in CuO by ball milling

    Directory of Open Access Journals (Sweden)

    Daqiang Gao

    2011-12-01

    Full Text Available In this work, we experimentally demonstrate that it is possible to induce ferromagnetism in CuO by ball milling without any ferromagnetic dopant. The magnetic measurements indicate that paramagnetic CuO is driven to the ferromagnetic state at room temperature by ball milling gradually. The saturation magnetization of the milled powders is found to increase with expanding the milling time and then decrease by annealing under atmosphere. The fitted X-ray photoelectron spectroscopy results indicate that the observed induction and weaken of the ferromagnetism shows close relationship with the valence charged oxygen vacancies (Cu1+-VO in CuO.

  14. EXTREME MANAGEMENT OF PERFORMANCE GRINDING OF LIMESTONE INTO TWO-CHAMBER BALL MILLS

    Directory of Open Access Journals (Sweden)

    UZHELOVSKY V. A.

    2016-02-01

    Full Text Available Problem statement. The productivity of ball mills is an important process parameter. Optimization of loading of the mill will get the maximum efficiency of grinding limestone. Analysis of theresent research. In the scientific work on the process control of grinding in ball mills, particularly interesting are the work of Alekseev B. V., Maksimenko A. A., Uteush E. V., Bapat D. D., Kaminsky A. D. It is proved that the assessment of management effectiveness limestone grinding in a ball mill is a multiobjective and must provide to achieve the highest possible performance and the required fineness of electricity at the lowest cost. A significant factor affecting the performance of the mill is utilization level of limestone. Purpose. Performance of two-chamber ball mill increased by maintaining an optimal level of loading of the drum limestone. Conclusions. 1. In Matlab package developed and investigated simulation model of extreme performance management of a ball mill by optimizing the filling level of the drum limestone. 2. Simulation model allows you to study the influence of various factors on the performance of the mill and determine the previous settings establish extreme regulator to obtain the desired transition process with a given accuracy at the stage of design work.

  15. Efficiency of ball milled South African bentonite clay for remediation of acid mine drainage

    CSIR Research Space (South Africa)

    Masindi, Vhahangwele

    2015-12-01

    Full Text Available The feasibility of using vibratory ball milled South African bentonite clay for neutralization and attenuation of inorganic contaminants from acidic and metalliferous mine effluents has been evaluated. Treatment of acid mine drainage (AMD...

  16. Peptide synthesis: ball-milling, in solution, or on solid support, what is the best strategy?

    OpenAIRE

    Ophélie Maurin; Pascal Verdié; Gilles Subra; Frédéric Lamaty; Jean Martinez; Thomas-Xavier Métro

    2017-01-01

    While presenting particularly interesting advantages, peptide synthesis by ball-milling was never compared to the two traditional strategies, namely peptide syntheses in solution and on solid support (solid-phase peptide synthesis, SPPS). In this study, the challenging VVIA tetrapeptide was synthesized by ball-milling, in solution, and on solid support. The three strategies were then compared in terms of yield, purity, reaction time and environmental impact. The results obtained enabled to dr...

  17. Effect of high-energy ball milling time on structural and magnetic properties of nanocrystalline cobalt ferrite powders

    Energy Technology Data Exchange (ETDEWEB)

    Cedeño-Mattei, Yarilyn, E-mail: yarilyn.cedeno@upr.edu [Department of Chemistry, University of Puerto Rico—Mayagüez Campus, Mayagüez, PR 00681 (Puerto Rico); Perales-Pérez, Oscar [Department of Chemistry, University of Puerto Rico—Mayagüez Campus, Mayagüez, PR 00681 (Puerto Rico); Department of Engineering Science and Materials, University of Puerto Rico—Mayagüez Campus, Mayagüez, PR 00681 (Puerto Rico); Uwakweh, Oswald N.C. [Department of Engineering Science and Materials, University of Puerto Rico—Mayagüez Campus, Mayagüez, PR 00681 (Puerto Rico)

    2013-09-15

    Cobalt ferrite nanocrystals synthesized by conventional and size-controlled coprecipitation methods were treated by high-energy ball milling, HEBM, in order to study the effect of crystal size reduction and/or strain on the resulting magnetic properties. Processed nanocrystals were characterized by X-ray diffraction, Brunauer, Emmett, and Teller surface area analysis, transmission electron microscopy (TEM), and vibrating sample magnetometry. The cobalt ferrite nanocrystals exhibited crystal size reduction from initial values (average crystallite sizes of 12±1 nm and 18±3 nm, respectively) down to 10 nm after HEBM for 10 h. The specific surface area was decreased by milling (from 96.5 to 59.4 m{sup 2}/g; for the 12 nm cobalt ferrite nanocrystals), due to particles aggregation. TEM analyses corroborated the aggregation of the nanoparticles at such long milling times. The same cobalt ferrite nanocrystals exhibited a rise in coercivity from 394 to 560 Oe after 5 h ball milling which was attributed to the introduction of strain anisotropy, namely point defects, as suggested by the systematic shift of the diffraction peaks towards higher angles. In turn, the magnetic characterization of the starting 18 nm-nanocrystals reported a drop in coercivity from 4506 Oe to 491 Oe that was attributed predominantly to size reduction within the single domain region. A correlation between particle size, cationic distribution, and HEBM processing conditions became evident. - Highlights: • Effect of ball milling on the structural and magnetic properties of cobalt ferrite. • Prolonged milling promotes interparticle aggregation. • Tunable coercivity due to crystal size, strain, and cation distribution.

  18. Reliable Mechanochemistry: Protocols for Reproducible Outcomes of Neat and Liquid Assisted Ball-mill Grinding Experiments.

    Science.gov (United States)

    Belenguer, Ana M; Lampronti, Giulio I; Sanders, Jeremy K M

    2018-01-23

    The equilibrium outcomes of ball mill grinding can dramatically change as a function of even tiny variations in the experimental conditions such as the presence of very small amounts of added solvent. To reproducibly and accurately capture this sensitivity, the experimentalist needs to carefully consider every single factor that can affect the ball mill grinding reaction under investigation, from ensuring the grinding jars are clean and dry before use, to accurately adding the stoichiometry of the starting materials, to validating that the delivery of solvent volume is accurate, to ensuring that the interaction between the solvent and the powder is well understood and, if necessary, a specific soaking time is added to the procedure. Preliminary kinetic studies are essential to determine the necessary milling time to achieve equilibrium. Only then can exquisite phase composition curves be obtained as a function of the solvent concentration under ball mill liquid assisted grinding (LAG). By using strict and careful procedures analogous to the ones here presented, such milling equilibrium curves can be obtained for virtually all milling systems. The system we use to demonstrate these procedures is a disulfide exchange reaction starting from the equimolar mixture of two homodimers to obtain at equilibrium quantitative heterodimer. The latter is formed by ball mill grinding as two different polymorphs, Form A and Form B. The ratio R = [Form B] / ([Form A] + [Form B]) at milling equilibrium depends on the nature and concentration of the solvent in the milling jar.

  19. Effect of chromium and aluminum addition on anisotropic and microstructural characteristics of ball milled nanocrystalline iron

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajiv, E-mail: rajiv06484met@gmail.com [IITB-Monash Research Academy, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Department of Mechanical and Aerospace Engineering, Monash University, VIC 3800 Australia (Australia); Joardar, Joydip [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad (India); Singh Raman, R.K. [Department of Mechanical and Aerospace Engineering, Monash University, VIC 3800 Australia (Australia); Department of Chemical Engineering, Monash University, VIC 3800 Australia (Australia); Raja, V.S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Joshi, S.V. [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad (India); Parida, S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2016-06-25

    Prior studies on synthesis of nanocrystalline elements have discussed the effect of ball milling on lattice parameter, crystallite size, and micro-strain. For elemental milled powders, the anisotropic peak broadening does not change with increasing milling time. However, the effect of alloying addition on the anisotropic behavior of ball milled nanocrystalline powders remains an unexplored area. Here we report the effect of chromium and aluminum addition on the anisotropic behavior of iron in nanocrystalline Fe–20Cr–5Al (wt%) alloy powders synthesized by ball milling. The experimental results show that the anisotropic behavior of iron changes towards isotropic with milling. This change was also correlated to the theoretically calculated anisotropic factor from the change in elastic constant of iron due to milling. Addition of alloying elements exhibited a monotonic rise in the lattice parameter with crystallite size, which was attributed to the excess grain boundary interfacial energy and excess free volume at grain boundaries. Transmission electron microscopy image confirmed the crystallite size and nature of dislocation obtained using modified Williamson-Hall method. - Highlights: • Structural evolution in Fe–20Cr–5Al alloy during ball milling is reported. • Effect of alloying addition on the anisotropic behavior of iron was studied. • Agreement in anisotropic factor calculated theoretically and experimentally.

  20. Phase Transformation and Magnetic Property of Ni-Mn-Ga Powders Prepared by Dry Ball Milling

    Science.gov (United States)

    Tian, B.; Chen, F.; Tong, Y. X.; Li, L.; Zheng, Y. F.

    2012-12-01

    This study investigated the phase transformations and magnetic properties of Ni-Mn-Ga alloy powders prepared by dry ball milling in argon atmosphere. The Fe and Cr elements were found to be introduced in the alloy after ball milling, which should result from the severe collision and friction among the particles, balls, and vial. The x-ray diffraction result indicated that the Fe and Cr elements should have alloyed with the Ni-Mn-Ga matrix. The martensitic transformation temperature and Curie temperature of the 800 °C annealed powders decreased by ~33 °C and increased by ~28 °C, respectively, as compared to that of the bulk alloy. The comprehensive effect of the changing of valence electron concentration of the alloy due to the introduction of Fe and Cr and the grain refinement of the alloy caused by ball milling should be responsible for the reduction of martensitic transformation temperature. The saturation magnetization of the 800 °C annealed powders became larger (~5 emu/g) than that of the bulk alloy. The enhancement of magnetic properties, such as the increase of Curie temperature and enhancement of saturation magnetization of the annealed Ni-Mn-Ga powders, should be attributed to the increase of magnetic exchange caused by introduction of Fe in the alloy. The contaminations of Fe and Cr elements emerging from the dry ball milling process changed the phase transformation and magnetic properties of the Ni-Mn-Ga alloy. Therefore, the dry ball milling process is difficult to control the contamination from the milling medium and not suitable to prepare Ni-Mn-Ga powders. On the contrary, the wet ball milling method under liquid medium should be a better method to prevent the contamination and fabricate pure Ni-Mn-Ga ferromagnetic shape memory alloy powders.

  1. Comparison of characteristics of hydroxyapatite powders synthesized from cuttlefish bone via precipitation and ball milling techniques

    Science.gov (United States)

    Faksawat, K.; Kaewwiset, W.; Limsuwan, P.; Naemchanthara, K.

    2017-09-01

    The aim of this work was to compare characteristics of hydroxyapatite synthesized by precipitation and ball milling techniques. The cuttlefish bone powder was a precursor in calcium source and the di ammonium hydrogen orthophosphate powders was a precursor in phosphate source. The hydroxyapatite was synthesized by the both techniques such as precipitation and ball milling techniques. The phase formation, chemical structure and morphology of the both hydroxyapatite powders have been examined by X-ray diffractometer (XRD), Fourier transform infrared spectroscope (FTIR) and field emission scanning electron microscope (FESEM), respectively. The results show that the hydroxyapatite synthesized by precipitation technique formed hydroxyapatite phase slower than the hydroxyapatite synthesized by ball milling technique. The FTIR results show the chemical structures of sample in both techniques are similar. The morphology of the hydroxyapatite from the both techniques were sphere like shapes and particle size was about in nano scale. The average particle size of the hydroxyapatite by ball milling technique was less than those synthesized by precipitation technique. This experiment indicated that the ball milling technique take time less than the precipitation technique in hydroxyapatite synthesis.

  2. Effect of annealing on the magnetic properties of ball milled NiO powders

    Energy Technology Data Exchange (ETDEWEB)

    Kisan, Bhagaban [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Saravanan, P. [Defence Metallurgical Research laboratory, Hyderabad 500058 (India); Layek, Samar; Verma, H.C. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Hesp, David; Dhanak, Vinod [Department of Physics, University of Liverpool, Liverpool L69 3BX (United Kingdom); Krishnamurthy, Satheesh [Materials Engineering, The Open University, Milton Keynes MK7 6AA (United Kingdom); Perumal, A., E-mail: perumal@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

    2015-06-15

    We report systematic investigations on structural and magnetic properties of nanosized NiO powders prepared by the ball milling process followed by systematic annealing at different temperatures. Both as-milled and annealed NiO powders exhibit face centered cubic structure, but average crystallite size decreases (increases) with increasing milling time (annealing temperature). Pure NiO exhibits antiferromagnetic nature, which transforms into ferromagnetic one with moderate moment at room temperature with decreasing crystallite size. The on-set of ferromagnetic behavior in the as-milled powders was observed at higher temperatures (>750 K) as compared to bulk Ni (~630 K). On the other hand, annealing of as-milled powders showed a large reduction in magnetic moment and the rate of decrease of moment strongly depends on the milling conditions. The observed properties are discussed on the basis of crystallite size variation, defect density, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. - Highlights: • Preparation of fine NiO powder using top-to-bottom approach using planetary ball mill. • Effect of milling on instituting room temperature ferromagnetism with size reduction. • Stability of ferromagnetic properties at high temperatures in milled NiO powders • Effect of annealing process on the structural properties of milled NiO powders. • Understanding the origin of ferromagnetism at 300 K in NiO powders through annealing.

  3. Microstructure and morphological study of ball-milled metal matrix nanocomposites

    Science.gov (United States)

    Afkham, Y.; Khosroshahi, R. Azari; Kheirifard, R.; Mousavian, R. Taherzadeh; Brabazon, D.

    2017-08-01

    Due to the difficulty of preparation and beneficial properties achievable, copper and iron matrix nanocomposites are materials for which fabrication via the powder metallurgy route is attracting increasing research interest. The presence of ceramic nanoparticles in their matrix can lead to considerable changes in the microstructure and morphology. The effects of the type of metallic matrix and ceramic nanoparticle on the distribution of nano reinforcements and the morphology of ball-milled composite powders were evaluated in this study. For this purpose, 25 wt % of Al2O3 and SiC nanoparticles were separately ball-milled in the presence of iron and copper metals. The SEM, FESEM, and XRD results indicated that as-received nanoparticles, which were agglomerated before milling, were partially separated and embedded in the matrix of both the metals after the initial stages of ball milling, while prolonged milling was not found to further affect the distribution of nanoparticles. It was also observed that the Al2O3 phase was not thermodynamically stable during ball milling with copper powders. Finally, it was found that the presence of nanoparticles considerably reduce the average size of metallic powder particles.

  4. Structure and magnetic properties of NiZn ferrite/SiO{sub 2} nanocomposites synthesized by ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Pozo Lopez, G., E-mail: gpozo@famaf.unc.edu.a [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Instituto de Fisica Enrique Gaviola - CONICET (Argentina); Silvetti, S.P. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Instituto de Fisica Enrique Gaviola - CONICET (Argentina); Urreta, S.E. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Carreras, A.C. [Instituto de Investigaciones en Tecnologia Quimica - CONICET - UNSL, San Luis, 5700 (Argentina)

    2010-09-03

    Magnetic NiZnFe{sub 2}O{sub 4}/SiO{sub 2} nanocomposites are synthesized by ball-milling a mixture of crystalline {alpha}-Fe{sub 2}O{sub 3}, NiO, ZnO and SiO{sub 2} powders. Crystallographic phases appearing during milling, their particle sizes and lattice parameters are determined from X-ray diffraction (XRD) measurements and the morphology of the as-milled powders observed by scanning electron microscopy (SEM). Room temperature hysteresis properties are characterized by vibrating sample magnetometry. The milling process, up to 260 h, promotes the progressive amorphization of the powders and the formation of different phases, such as NiZn-ferrite, {alpha}-Fe and Fe{sub 2}SiO{sub 4}. For milling times smaller than 80 h, the complete transformation of the precursor oxides into NiZn-ferrite is only achieved after annealing the as-milled powders for 1 h in air at 1273 K. This heat treatment favors the formation of NiZn-ferrite in detriment of the precursor oxides. On the other hand, annealing in air the powder milled 260 h, essentially amorphous, results in the formation of both hematite and NiZn-ferrite in the amorphous silica. When the powders milled for 260 h are heat treated in argon atmosphere, a biphase composite is obtained, with NiZn-ferrite crystallites of about 65 nm dispersed in an amorphous silica matrix. This last powder presents the highest values of saturation magnetization (29.87 Am{sup 2}/kg) and coercivity (25.7 kA/m), being the latter two orders of magnitude larger than that of bulk NiZn-ferrite.

  5. Performance Study of Graphite Anode Slurry in Lithium-ion Flow Battery by Ball Milling

    Directory of Open Access Journals (Sweden)

    FENG Cai-mei

    2018-02-01

    Full Text Available Graphite anode slurry of lithium-ion flow battery was prepared by the method of ball milling. The morphology, conductivity, specific capacity and cycle performance of graphite anode slurry were studied. Results show that the addition of conductive carbon material can improve the suspension stability of the electrode slurry; the ball milling process can not only improve the suspension stability but also reduce the resistivity of the mixed powders of graphite and conductive carbon materials, the ball milling effect is satisfactory when the mass ratio of the balls and the solid particles is 5:1, but too high ratio of the milling ball and the solid materials can destroy the layer structure of the graphite and affect the stability of the slurry. Increasing the fraction of the graphite and conductive carbon materials can form stable electrical network structure in the slurry and improve the reversible capacity; at the premise of keeping the flowability of the electrode slurry, the reversible specific capacity can be more than 40mAh/g. The capacity loss of graphite anode slurry mainly occurs in the first charging-discharging process, as the increase of the cycles, the capacity loss rate decreases, the capacity goes stable after 5 cycles.

  6. Effect of ball milling on the physicochemical properties of atorvastatin calcium sesquihydrate: the dissolution kinetic behaviours of milled amorphous solids.

    Science.gov (United States)

    Kobayashi, Makiko; Hattori, Yusuke; Sasaki, Tetsuo; Otsuka, Makoto

    2017-01-01

    The purposes of this study were to clarify the amorphization by ball milling of atorvastatin calcium sesquihydrate (AT) and to analyse the change in dissolution kinetics. The amorphous AT was prepared from crystal AT by ball milling and analysed in terms of the changes of its physicochemical properties by powder X-ray diffraction analysis (XRD), thermal analysis and infrared spectroscopy (IR). Moreover, to evaluate the usefulness of the amorphous form for pharmaceutical development, intrinsic solubility of the ground product was evaluated using a dissolution kinetic method. The XRD results indicated that crystalline AT was transformed into amorphous solids by more than 30-min milling. The thermal analysis result suggested that chemical potential of the ground AT are changed significantly by milling. The IR spectra of the AT showed the band shift from the amide group at 3406 cm-1 with an intermolecular hydrogen bond to a free amide group at 3365 cm-1 by milling. The dissolution of amorphous AT follows a dissolution kinetic model involving phase transformation. The initial dissolution rate of the ground product increased with the increase in milling time to reflect the increase in the intrinsic solubility based on the amorphous state. © 2016 Royal Pharmaceutical Society.

  7. Ball milling improves extractability and affects molecular properties of psyllium (Plantago ovata Forsk) seed husk arabinoxylan.

    Science.gov (United States)

    Van Craeyveld, Valerie; Delcour, Jan A; Courtin, Christophe M

    2008-12-10

    Psyllium (Plantago ovata Forsk) seed husk (PSH) is very rich in arabinoxylan (AX). However, its high gelling capacity and the complex nature of the AX make it difficult to process. In this study, ball milling was investigated as a tool for enhancing PSH AX water extractability and molecular mass (MM). A 48 h laboratory-scale ball mill treatment under standardized optimal conditions reduced the PSH average particle size from 161 microm for the untreated sample to 6 microm. Concurrently, it increased the water-extractable AX (WE-AX) level from 13 (untreated PSH) to 90% of the total PSH AX. While the WE-AX of the untreated PSH had a peak MM of 216 kDa and an arabinose to xylose (A/X) ratio of 0.20, WE-AX fragments from ball mill-pretreated PSH had a peak MM of 22 kDa and an A/X ratio of 0.31. Ball milling further drastically reduced the intrinsic viscosity of PSH extracts and their water-holding capacity. Prolonged treatment brought almost all AX (98%) in solution and yielded WE-AX fragments with an even higher A/X ratio (0.42) and a lower peak MM (11 kDa). While impact and jet milling of PSH equally led to significant reductions in particle size, these technologies only marginally affected the water extractability of PSH AX. This implies that ball milling affects PSH particles and their constituent molecules differently than impact and jet milling.

  8. Peptide synthesis: ball-milling, in solution, or on solid support, what is the best strategy?

    Directory of Open Access Journals (Sweden)

    Ophélie Maurin

    2017-10-01

    Full Text Available While presenting particularly interesting advantages, peptide synthesis by ball-milling was never compared to the two traditional strategies, namely peptide syntheses in solution and on solid support (solid-phase peptide synthesis, SPPS. In this study, the challenging VVIA tetrapeptide was synthesized by ball-milling, in solution, and on solid support. The three strategies were then compared in terms of yield, purity, reaction time and environmental impact. The results obtained enabled to draw some strengths and weaknesses of each strategy, and to foresee what will have to be implemented to build more efficient and sustainable peptide syntheses in the near future.

  9. Low-temperature magnetic behavior of ball-milled copper ferrite

    DEFF Research Database (Denmark)

    Goya, G.F.; Rechenberg, H.R.; Jiang, Jianzhong

    1999-01-01

    We present a study on magnetic properties of CuFe2O4 nanoparticles, produced by high-energy ball milling. The series of samples obtained, with average particle sizes LFAN alpha d RTAN ranging from 61 nm to 9 nm, display increasing relaxation effects at room temperature. Irreversibility of the mag......We present a study on magnetic properties of CuFe2O4 nanoparticles, produced by high-energy ball milling. The series of samples obtained, with average particle sizes LFAN alpha d RTAN ranging from 61 nm to 9 nm, display increasing relaxation effects at room temperature. Irreversibility...

  10. The Effect of High Energy Ball Milling on the Dynamic Response of Aluminum Powders

    Science.gov (United States)

    Beason, Matthew T.; Justice, Andrew W.; Gunduz, Ibrahim E.; Son, Steven F.

    2017-06-01

    Ball milling is an effective method to enhance the reactivity of intermetallic reactives by reducing characteristic diffusions distances. During this process, ductile reactants are mixed into a lamellar material with nanoscale features, resulting in significant strain hardening. Plate impact experiments using a single stage light gas gun have been performed to evaluate the effect of high energy ball milling (HEBM) on the mechanical properties and dynamic response of cold pressed aluminum compacts. The average grain size of the milled material is evaluate and suggested as a method of correlating the measured response to the properties of milled composites. This material is based upon work supported by the Department of Energy, National Nuclear Security Administration, under Award Number(s) DE-NA0002377, as well as individual funding (Beason) by the Department of Defense through the NDSEG.

  11. THEORETICAL AND EXPERIMENTAL STUDIES OF ENERGY-EFFICIENT GRINDING PROCESS OF CEMENT CLINKER IN A BALL MILL

    Directory of Open Access Journals (Sweden)

    Kuznetsova M.M.

    2014-08-01

    Full Text Available The article presents results of theoretical and experimental research of grinding process of bulk materials in a ball mill. The new method of determination of energy efficiently mode of operation of ball mills in a process of a cement clinker grinding is proposed and experimentally tested.

  12. FePt magnetic particles prepared by surfactant-assisted ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Velasco, V., E-mail: vvjimeno@fis.ucm.es [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, P.O. Box 155, Las Rozas 28230 (Spain); Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid 28040 (Spain); Hernando, A.; Crespo, P. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, P.O. Box 155, Las Rozas 28230 (Spain); Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid 28040 (Spain)

    2013-10-15

    High-energy ball milling of Fe and Pt elemental powders has been carried out under dry and wet (in presence of solvent and surfactants) conditions. Dry milling leads to the formation of the disordered FCC-FePt alloy whereas by the wet milling procedure the main process is the decrease of Fe and Pt particle size, although some dissolution of Pt into Fe grains cannot be ruled out, and no hint of the formation of the FCC-FePt phase is observed even to milling times up to 20 h, as X-ray diffraction, electron microscopy and Mössbauer spectroscopy indicates. The as-milled particles were annealed at 600 °C for 2 h under Ar atmosphere. It is noticed that the disordered fcc-FePt phase observed in particles milled under dry conditions transform to ordered fct phase characterized by a hard magnetic behavior with a coercive field up to 10,000 Oe. However, those particles milled in the surfactant/solvent medium exhibit a soft magnetic behavior with a coercive field of 600 Oe. These results indicate that wet high-energy ball milling is not an adequate technique for obtaining single-phase FePt particles. - Highlights: • FePt particles have been obtained by high-energy ball milling. • In the presence of surfactants and solvents, almost no alloying process takes place. • After annealing, the coercive field of the FePt alloy particles increases from 150 Oe to 10,000 Oe.

  13. The analysis of instantaneous tool displacements during precise ball end milling

    Directory of Open Access Journals (Sweden)

    Wojciechowski Szymon

    2017-01-01

    Full Text Available The paper presents the quantitative and qualitative analysis of monolithic ball end mill’s instantaneous displacements generated during precise milling of inclined surfaces. The conducted experiment involves the measurements of tool’s joining part displacements with the application of laser displacement sensor and cutting forces with piezoelectric dynamometer. The milling tests were carried out for the hardened alloy 55NiCrMoV6 steel in a range of variable feed per tooth and surface inclination angle values. The obtained results can be applied for the selection of effective milling parameters allowing the improvement of machined surface finish.

  14. Mechanically Induced Graphite-Nanodiamonds-Phase Transformations During High-Energy Ball Milling

    Science.gov (United States)

    El-Eskandarany, M. Sherif

    2017-05-01

    Due to their unusual mechanical, chemical, physical, optical, and biological properties, nearly spherical-like nanodiamonds have received much attention as desirable advanced nanomaterials for use in a wide spectrum of applications. Although, nanodiamonds can be successfully synthesized by several approaches, applications of high temperature and/or high pressure may restrict the real applications of such strategic nanomaterials. Distinct from the current preparation approaches used for nanodiamonds preparation, here we show a new process for preparing ultrafine nanodiamonds (3-5 nm) embedded in a homogeneous amorphous-carbon matrix. Our process started from high-energy ball milling of commercial graphite powders at ambient temperature under normal atmospheric helium gas pressure. The results have demonstrated graphite-single wall carbon nanotubes-amorphous-carbon-nanodiamonds phase transformations carried out through three subsequent stages of ball milling. Based on XRD and RAMAN analyses, the percentage of nanodiamond phase + C60 (crystalline phase) produced by ball milling was approximately 81%, while the amorphous phase amount was 19%. The pressure generated on the powder together the with temperature increase upon the ball-powder-ball collision is responsible for the phase transformations occurring in graphite powders.

  15. Magnetic properties of ball-milled TbFe2 and TbFe2B

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 27; Issue 2. Magnetic properties of ... Amorphous materials; intermetallic compounds; magnetic materials; magnetic properties. Abstract. The magnetic properties of ball-milled TbFe2 and TbFe2B were studied by magnetization measurements. X-ray diffraction studies on ...

  16. Crystal growth and the steady-state grain size during high-energy ball-milling

    DEFF Research Database (Denmark)

    Mørup, Steen; Jiang, Jianzhong; Bødker, Franz

    2001-01-01

    The change in crystal size during high-energy ball-milling of hematite and zinc sulphide powders with initial average crystal size of 8 nm and 4 nm, respectively, has been investigated by X-ray powder diffraction and transmission electron microscopy. It is found that the crystal size increases...

  17. Non-equilibrium microscale thermomechanical modeling of bimetallic particulate fractal structures during ball milling fabrication

    Science.gov (United States)

    Aureli, Matteo; Doumanidis, Constantine C.; Gunduz, I. E.; Hussien, Aseel Gamal Suliman; Liao, Yiliang; Jaffar, Syed Murtaza; Rebholz, Claus; Doumanidis, Charalabos C.

    2017-07-01

    Nanostructured bimetallic reactive multilayers can be conveniently produced by ball milling of elemental powders. This research explores the non-equilibrium microscale conductive thermal transport in ball-milled particulate fractal structures during fabrication, arising from heat dissipation by bulk plastic deformation and surface friction. Upon impactor collisions, temperature increments are determined at interface joints and domain volumes using Green's functions, mirrored by source images with respect to warped ellipsoid domain boundaries. Heat source efficiency is calibrated via laboratory data to compensate for thermal expansion and impactor inelasticity, and the thermal analysis is coupled to a dynamic mechanics model of the particulate fracture. This thermomechanical model shows good agreement with the fractal dimensions of the observed microstructure from ball milling experiments. The model is intended to provide a comprehensive physical understanding of the fundamental process mechanism. In addition, the model could serve as a real-time thermal observer for closed-loop process control, as well as for interfacial diffusion and reaction analysis during ball milling.

  18. Effects of high energy ball milling on synthesis and characteristics of Ti-Mg alloys

    CSIR Research Space (South Africa)

    Chikwanda, HK

    2008-01-01

    Full Text Available . Young-Soon Kwon, Ji-Soon Kim and Cheol-Eeh Kim, Decomposition and crystallisation induced by high energy ball-milling, Solid State Phenomena vol 119 (2007) pp 1-4. 2. Fusheng Sun and F H (Sam) Froes, Synthesis and characterisation of mechanical...

  19. A vertical ball mill as a new reactor design for biomass hydrolysis and fermentation process

    DEFF Research Database (Denmark)

    de Assis Castro, Rafael Cunha; Mussatto, Solange I.; Conceicao Roberto, Inês

    2017-01-01

    A vertical ball mill (VBM) reactor was evaluated for use in biomass conversion processes. The effects of agitation speed (100–200 rpm), number of glass spheres (0–30 units) and temperature (40–46 °C) on enzymatic hydrolysis of rice straw and on glucose fermentation by a thermotolerant Kluyveromyc...

  20. Effect of ball milling energy on rheological and thermal properties of amaranth flour.

    Science.gov (United States)

    Roa, Diego F; Baeza, Rosa I; Tolaba, Marcela P

    2015-12-01

    Pearled amaranth grains obtained by abrasive milling were processed by planetary ball milling to produce amaranth flours. The influence of milling energy on rheological and thermal behavior of amaranth flour dispersions and stability during 24 h storage at 4 °C were investigated based on a factorial design. The rheological behavior of flour dispersions (4 % and 8 % w/v) was determined using a rotational viscometer, while gelatinization degree was determined by differential scanning calorimetry as a measure of structural changes.The power law model was found to be suitable in expressing the relationship between shear stress and shear rate. Flour dispersions showed a pseudoplastic behavior. However this character decreased with the storage being dependent on flour concentration and milling energy. A decrease of the consistency index and an increase of the flow behavior index were observed as a result of the increasing milling energy. Gelatinization enthalpy decrease showed the loss of crystalline structure due to ball milling. Amaranth flour dispersions presented increasing stability during storage. It was observed, that the stability changed with the concentration of amaranth flours.Thus, more stable dispersions were obtained as the flour concentration increased. The highly milled sample was the most stable sample during the storage.

  1. Defect induced electronic states and magnetism in ball-milled graphite.

    Science.gov (United States)

    Milev, Adriyan; Dissanayake, D M A S; Kannangara, G S K; Kumarasinghe, A R

    2013-10-14

    The electronic structure and magnetism of nanocrystalline graphite prepared by ball milling of graphite in an inert atmosphere have been investigated using valence band spectroscopy (VB), core level near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and magnetic measurements as a function of the milling time. The NEXAFS spectroscopy of graphite milled for 30 hours shows simultaneous evolution of new states at ~284.0 eV and at ~290.5 eV superimposed upon the characteristic transitions at 285.4 eV and 291.6 eV, respectively. The modulation of the density of states is explained by evolution of discontinuities within the sheets and along the fracture lines in the milled graphite. The magnetic measurements in the temperature interval 2-300-2 K at constant magnetic field strength show a correlation between magnetic properties and evolution of the new electronic states. With the reduction of the crystallite sizes of the graphite fragments, the milled material progressively changes its magnetic properties from diamagnetic to paramagnetic with contributions from both Pauli and Curie paramagnetism due to the evolution of new states at ~284 and ~290.5 eV, respectively. These results indicate that the magnetic behaviour of ball-milled graphite can be manipulated by changing the milling conditions.

  2. Considerations Concerning the Dynamics of Vibratory Mills Used in Powders’ Mechanical Milling Process

    Directory of Open Access Journals (Sweden)

    Radu Panaitescu-Liess

    2010-01-01

    Full Text Available Dynamic mechanical milling process in a powder mill was studied by analyzing the vibratory effects of vibration and shock phenomena on the material microstructure ground. During the milling process, there were noticed both distinct modes of ball motion: the one generated by the periodic vibration and the one produced by chaotic vibration.

  3. Synthesis of magnetically exchange coupled SrFe12O19/FeCo composites through cryogenic ball milling

    Science.gov (United States)

    Pang, Ning; Ye, Feng; Jiang, Ying

    2017-07-01

    SrFe12O19/FeCo composite particles with different mass ratios of SrFe12O19 to FeCo were synthesized through a cryogenic ball milling process. The corresponding products were characterized with scanning electron microscopy (SED), transmission electron microscopy (TEM), x-ray diffraction (XRD) and vibrating sample magnetometer (VSM) for crystal morphology, elemental distribution, crystal phases, and magnetic properties. The results showed that when the mass percentage of FeCo was less than 15%, smooth magnetic hysteresis loops could be obtained from SrFe12O19/FeCo composite particles, indicating effective magnetic exchange coupling between the SrFe12O19 and FeCo particles. A further FeCo mass increase resulted in kinks in the magnetic hysteresis loop and destroyed the magnetic exchange coupling. As a comparison, room temperature ball milling of SrFe12O19/FeCo (95/5 wt%) cannot achieve magnetic exchange coupling between SrFe12O19 and FeCo due to FeCo nanoparticle agglomeration.

  4. Formation of budesonide/α-lactose glass solutions by ball-milling

    Science.gov (United States)

    Dudognon, E.; Willart, J. F.; Caron, V.; Capet, F.; Larsson, T.; Descamps, M.

    2006-04-01

    The possibility to obtain amorphous budesonide stabilised by blending with an excipient characterised by a higher glass transition temperature, namely α-lactose, has been studied. We carried out the mixing of the two compounds at room temperature by ball-milling. The four obtained blends (containing, respectively, 10, 30, 50 and 70% w of budesonide) are X-ray amorphous and exhibit a single glass transition located between the ones of pure milled crystalline compounds. This revealed that the two amorphous phases are miscible whatever the composition and sufficiently mixed to relax as a whole. Ball-milling thus appears as a powerful tool to form amorphous molecular alloys with enhanced stability properties.

  5. Scale-up of organic reactions in ball mills: process intensification with regard to energy efficiency and economy of scale.

    Science.gov (United States)

    Stolle, Achim; Schmidt, Robert; Jacob, Katharina

    2014-01-01

    The scale-up of the Knoevenagel-condensation between vanillin and barbituric acid carried out in planetary ball mills is investigated from an engineering perspective. Generally, the reaction proceeded in the solid state without intermediate melting and afforded selectively only one product. The reaction has been used as a model to analyze the influence and relationship of different parameters related to operation in planetary ball mills. From the viewpoint of technological parameters the milling ball diameter, dMB, the filling degree with respect to the milling balls' packing, ΦMB,packing, and the filling degree of the substrates with respect to the void volume of the milling balls' packing, ΦGS, have been investigated at different reaction scales. It was found that milling balls with small dMB lead to higher yields within shorter reaction time, treaction, or lower rotation frequency, rpm. Thus, the lower limit is set considering the technology which is available for the separation of the milling balls from the product after the reaction. Regarding ΦMB,packing, results indicate that the optimal value is roughly 50% of the total milling beakers' volume, VB,total, independent of the reaction scale or reaction conditions. Thus, 30% of VB,total are taken by the milling balls. Increase of the initial batch sizes changes ΦGS significantly. However, within the investigated parameter range no negative influence on the yield was observed. Up to 50% of VB,total can be taken over by the substrates in addition to 30% for the total milling ball volume. Scale-up factors of 15 and 11 were realized considering the amount of substrates and the reactor volume, respectively. Beside technological parameters, variables which influence the process itself, treaction and rpm, were investigated also. Variation of those allowed to fine-tune the reaction conditions in order to maximize the yield and minimize the energy intensity.

  6. Microstructural Evolution, Thermodynamics, and Kinetics of Mo-Tm2O3 Powder Mixtures during Ball Milling

    Directory of Open Access Journals (Sweden)

    Yong Luo

    2016-10-01

    Full Text Available The microstructural evolution, thermodynamics, and kinetics of Mo (21 wt % Tm2O3 powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm2O3 to be decomposed and then dissolved into Mo crystal. After 96 h of ball milling, Tm2O3 was dissolved completely and the supersaturated nanocrystalline solid solution of Mo (Tm, O was obtained. The Mo lattice parameter increased with increasing ball-milling time, opposite for the Mo grain size. The size and lattice parameter of Mo grains was about 8 nm and 0.31564 nm after 96 h of ball milling, respectively. Ball milling induced the elements of Mo, Tm, and O to be distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo (21 wt % Tm2O3, it was mechanical work, not the negative heat of mixing, which provided the driving force to form a supersaturated nanocrystalline Mo (Tm, O solid solution.

  7. Transformations in oxides induced by high-energy ball-milling.

    Science.gov (United States)

    Šepelák, Vladimir; Bégin-Colin, Sylvie; Le Caër, Gérard

    2012-10-21

    This paper, by no means exhaustive, focuses on high-energy ball-milling of oxides, on their mechanically induced changes and on the consequences of such changes on their physical and chemical properties. High-energy ball-milling offers a fortunate combination of technical simplicity and of complexity both of physical mechanisms which act during milling and of mechanosynthesized materials. Its basic interest, which stems from the large diversity of routes it offers to prepare oxides either directly or indirectly, is illustrated with various families of oxides. The direct path is to be favoured when as-milled oxides are of interest per se because of their nanocrystalline characteristics, their defects or their modified structures which result from mechanically driven phase transformations. The indirect path consists of a sequence of steps starting with mechanically activated oxides which may be subsequently just annealed or submitted to a combination of thermal treatments, with the possible occurrence of various chemical reactions, to prepare the sought-after materials with potential gains in processing temperatures and times. High energy ball-milling of oxides is more and more currently used to activate powders and to prepare nano-oxides at moderate temperatures. The interest of an activation step is well illustrated by the broad development of doped titania powders, synthesized by heat treatment of pre-ground reactants, for photocatalytic applications or to develop antibacterial materials. Another important class of applications of high-energy ball-milling is the formation of composites. It is exemplified here with the case of oxide-dispersed strengthened alloys whose properties are considerably improved by a dispersion of ultra-stable nanosized oxides whose formation mechanisms were recently described. The basic understanding of the mechanisms by which oxides or oxide mixtures evolve by high-energy ball-milling appears to be less advanced than it is for metallic

  8. Hydrogen Sorption Properties of the Intermetallic Mg2Ni Obtained by Using a Simoloyer Ball Milling

    Directory of Open Access Journals (Sweden)

    Bormann R.

    2010-07-01

    Full Text Available Intermetallic Mg2Ni was produced from elemental powder blends by mechanical alloying in a batch scale using a rotary horizontal mill (Simoloyer. Fast hydrogenation kinetics are obtained: 2.2 wt.% of hydrogen is absorbed within 10 minutes at 300 °C. Hydrogen sorption kinetics were further improved by adding Pd (1 mol% powder as a catalyst during ball milling. Crack formation and concomitant particle size reduction was observed by scanning electron microscopy after hydrogen cycling, which is attributed to internal stresses in the particles.

  9. Study on the Thermal Conductivity Characteristics of Graphene Prepared by the Planetary Ball Mill

    Directory of Open Access Journals (Sweden)

    Gwi-Nam Kim

    2016-09-01

    Full Text Available This study was designed to examine the physical disintegration of graphene (GN, an excellent heat conductor, by using the planetary ball mill, a simple and convenient means to produce particles arbitrarily. The conditions for the disintegration of GN were distinguished by the rotation of the planetary ball mill (200 rpm, 400 rpm, and 600 rpm and by the duration of its operation (30 min, 60 min, and 90 min, respectively. From the results, we saw that, when experimental conditions are 200 rpm with 60 min, the particle size was the smallest (at 328 nm and the results of thermal conductivity were the highest. In the absorbance results, GN was well dispersed because the value of its absorbance is high.

  10. Sintered Fe-Ni-Cu-Sn-C Alloys Made of Ball-Milled Powders

    Directory of Open Access Journals (Sweden)

    Romański A.

    2014-10-01

    Full Text Available The main objective of this paper was to perform sinterability studies of ball-milled Fe-12%Ni-6.4%Cu-1.6%Sn-0.6%C powders. A mixture of precisely weighed amounts of elemental iron, nickel and graphite, and pre-alloyed 80/20 bronze powders was ball-milled for 8, 30 and 120 hours. After cold-pressing at 400 MPa the specimens were sintered at 900oC for 30 minutes in a reducing atmosphere and subsequently tested for density and hardness as well as subjected to structural studies using scanning electron microscopy (SEM and X-ray diffraction (XRD analysis.

  11. Broadband Absorber for the Microwave Region Using Ball-Milled Graphite Gratings

    Science.gov (United States)

    Chen, Xiqiao; Zhang, Zilong; Wang, Zilin; Wang, Shuai; Heng, Liuyang; Zou, Yanhong

    2017-10-01

    A broadband absorber for the microwave region based on a dielectric structure with ball-milled graphite gratings has been proposed. In this absorber, electromagnetic waves in the frequency range of 5.4 to 18 GHz are absorbed efficiently with more than 90% absorptivity. The ball-milled graphite with high a imaginary part of its permittivity used in this work can exhibit dielectric loss to some extent, while there is almost no magnetic loss owing to its low permeability. By comparing the electric field of a single absorbing layer and our grating structure, we found that a λ/4 resonance mode with a narrowband property is excited in the single-layer structure, while the cavity-mode resonance and the edge diffraction effects are the main reasons for the broadband absorption of our designed grating structure. This result provides a guideline for microwave-absorbing materials to greatly extend their bandwidth using a simple structure.

  12. Tuned rolling-ball dampers for vibration control in wind turbines

    DEFF Research Database (Denmark)

    Chen, Junling; Georgakis, Christos T.

    2013-01-01

    With wind turbines growing in size and cost, it is necessary to reduce their dynamic responses and improve their fatigue lifetime. A passive tuned-mass damper (TMD) is a very efficient solution for vibration control in structures subjected to wind excitations. In this study, a tuned rolling......-ball damper characterized by single or multiple steel balls rolling in a spherical container is proposed to be mounted on the top of wind turbines to reduce the wind-induced vibration. A 1/20 scale shaking table model was developed to evaluate the control effectiveness of the damper. The wind-induced dynamic...... responses of the test model with and without TMD were obtained from the shaking table tests. The test results indicated that the rolling-ball dampers could effectively suppress the wind-induced vibration of wind turbines. The damper with three balls in one container had better control effectiveness than...

  13. An environmentally friendly ball milling process for recovery of valuable metals from e-waste scraps.

    Science.gov (United States)

    Zhang, Zhi-Yuan; Zhang, Fu-Shen; Yao, TianQi

    2017-10-01

    The present study reports a mechanochemical (MC) process for effective recovery of copper (Cu) and precious metals (i.e. Pd and Ag) from e-waste scraps. Results indicated that the mixture of K 2 S 2 O 8 and NaCl (abbreviated as K 2 S 2 O 8 /NaCl hereafter) was the most effective co-milling reagents in terms of high recovery rate. After co-milling with K 2 S 2 O 8 /NaCl, soluble metallic compounds were produced and consequently benefit the subsequent leaching process. 99.9% of Cu and 95.5% of Pd in the e-waste particles could be recovered in 0.5mol/L diluted HCl in 15min. Ag was concentrated in the leaching residue as AgCl and then recovered in 1mol/L NH 3 solution. XRD and XPS analysis indicated that elemental metals in the raw materials were transformed into their corresponding oxidation state during ball milling process at low temperature, implying that solid-solid phase reactions is the reaction mechanism. Based on the results and thermodynamic parameters of the probable reactions, possible reaction pathways during ball milling were proposed. Suggestion on category of e-waste for ball milling process was put forward according to the experiment results. The designed metal recovery process of this study has the advantages of highly recovery rate and quick leaching speed. Thus, this study offers a promising and environmentally friendly method for recovering valuable metals from e-waste. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Mechanochemical destruction of mirex co-ground with iron and quartz in a planetary ball mill.

    Science.gov (United States)

    Yu, Yunfei; Huang, Jun; Zhang, Wang; Zhang, Kunlun; Deng, Shubo; Yu, Gang

    2013-02-01

    Mechanochemical destruction (MCD) has been recognized as a promising non-combustion technology for the disposal of obsolete pesticides belonging to the persistent organic pollutants (POPs). Mirex, a termiticide ever used for many years in China, was ball milled in the presence of various reagent(s) in a planetary ball mill at room temperature to investigate the destruction efficiency. The ground samples were characterized and analyzed by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, gas chromatography (GC), and ion chromatography (Martins, Bicego et al.). Under the same conditions of mill rotary rate and charge ratio, the mixture of iron powder and quartz sand (Fe/SiO(2)) was found best in promoting the mirex destruction. Mirex was completed destroyed after 2 h grinding at a charge ratio of 36:1 (reagent/mirex, m/m) and a mill rotation speed of 550 rpm. No organic compound was detected by GC/μECD screening. The yield of water-soluble chlorine determined by ion chromatography (Martins, Bicego et al.) in the final residue accounted for 90.7% of chlorine in the original mirex, which indicated a nearly complete dechlorination. Signals of both graphite and amorphous carbon were found in the Raman spectra of the co-ground powder samples. With the main final degradation products of water soluble Cl and carbon, the mechanism of the mechanochemical destruction approach should be dechlorination followed by the carbonization. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Synthesis of hydroxyapatite from eggshell powders through ball milling and heat treatment

    Directory of Open Access Journals (Sweden)

    Shih-Ching Wu

    2016-03-01

    Full Text Available Every day, several million tons of eggshells are being generated as bio-waste across the world. This study demonstrates the synthesis of HA powder using dicalcium phosphate dehydrate (CaHPO4·2H2O, DCPD and eggshell powders via ball milling and subsequent heat treatment. The formation of HA phase can be initiated by sintering the 1 h milled sample at 1000 °C for 1 h, while pure HA phase can be obtained upon sintering the 10 h milled sample. Additionally, the final products composed of biphasic calcium phosphate (HA + β-TCP crystals can easily be prepared by ball milling for 5 h followed by heat treatment at 1000 °C for 1 h. The carbonate peaks observed in the FTIR analysis of the as-prepared HA closely matched those of A- and B-type carbonates, which is typical of the biological apatite. The elemental composition of the as-synthesized HA showed the presence of Ca, P, Mg, and Sr.

  16. Conductivity of the PGT Synthesized by the High Energy Ball Milling (HEBM

    Directory of Open Access Journals (Sweden)

    S. K. S. Parashar

    2013-01-01

    Full Text Available Nanocrystalline Pb1−3x/2GdxTiO3 (where x=0.01 abbreviated as PGT has been synthesised by high energy ball milling at room temperature. Milling was continuous and X-ray analysis shows that single phase tetragonal structure of nanocrystalline PGT was formed after 15 h milling. The average crystallite size was found to be 17 nm. The frequency dependent ac conductivity of the PGT ceramic was studied in the range 100–525°C. Complex impedance analysis suggested the dielectric relaxation to be of non-Debye type. The activation energy was found to be 1.04 ev. The mechanism of charge transport in nanocrystalline PGT was successfully explained by correlated hopping model.

  17. Formation of a 25 mol% Fe2O3-Al2O3 solid solution prepared by ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Mørup, Steen; Linderoth, Søren

    1996-01-01

    The phase transformation process of a 25 mol% Fe2O3-Al2O3 powder mixture during high-energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. A metastable solid solution of 25 mol % Fe2O3 in Al2O3 with corundum structure has successfully been prepared after a milling...

  18. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al₂O₃ Nanocomposite Synthesized by Ball Milling and Powder Metallurgy.

    Science.gov (United States)

    Toozandehjani, Meysam; Matori, Khamirul Amin; Ostovan, Farhad; Abdul Aziz, Sidek; Mamat, Md Shuhazlly

    2017-10-26

    The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al₂O₃ (Al-5Al₂O₃) has been investigated. Al-5Al₂O₃ nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al₂O₃ nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD) analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV), nano-hardness (HN), and Young's modulus (E) of Al-5Al₂O₃ nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.

  19. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al2O3 Nanocomposite Synthesized by Ball Milling and Powder Metallurgy

    Directory of Open Access Journals (Sweden)

    Meysam Toozandehjani

    2017-10-01

    Full Text Available The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al2O3 (Al-5Al2O3 has been investigated. Al-5Al2O3 nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al2O3 nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV, nano-hardness (HN, and Young’s modulus (E of Al-5Al2O3 nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.

  20. High-efficient production of boron nitride nanosheets via an optimized ball milling process for lubrication in oil.

    Science.gov (United States)

    Deepika; Li, Lu Hua; Glushenkov, Alexey M; Hait, Samik K; Hodgson, Peter; Chen, Ying

    2014-12-03

    Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1-0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5-1.5 μm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil.

  1. Microstructure and magnetic properties of nano-sized Ba-Al ferrite particles by high energy ball milling.

    Science.gov (United States)

    Kim, Bo Sik; Chang, Si Young

    2012-02-01

    The magnetic nano-structured Ba-Al ferrite powders were prepared by high energy ball milling under the conditions of various rotation rates and milling times. The micro structure was characterized by SEM, XRD and TEM, and the magnetic properties were obtained by VSM. As the rotation rate and milling time increased, the size of nano-sized particles gradually decreased. The high energy ball milling for 5 h without relation to the rotation rate drastically reduced the coercivity as a consequence of the formation of nano-sized particle with the amorphous structure. However, the coercivity gradually decreased with increasing the milling time, resulting from the decrease of particle size with maintaining the crystal structure.

  2. Tuning the length dispersion of multi-walled carbon nanotubes by ball milling

    Directory of Open Access Journals (Sweden)

    László Forró

    2013-09-01

    Full Text Available The statistical analysis of the length distribution of catalytic chemical vapour deposition synthesized multi-walled carbon nanotubes cut by planetary ball milling is reported. The nanotube lengths follow a log-normal distribution in a broad range of grinding time and rotational speed. We show that the scale parameter of the distribution, which equals the mean of the natural logarithm of the tube lengths, decreases linearly with the product of the duration time and the rotational speed. This relation can be used for tailoring nanotube lengths by a suitable choice of process parameters for a wide range of applications.

  3. Mechanochemical synthesis of PbF2 by high energy ball milling

    Science.gov (United States)

    Heise, M.; Scholz, G.; Kemnitz, E.

    2017-10-01

    Lead(II)-fluoride was successfully prepared by high energy ball milling and for comparison by classical thermal solid state chemical reaction. The influence of different starting materials, fluorinating agents and synthesis methods on the formation of the orthorhombic α-phase and the cubic β-phase was investigated. XRD analysis provided insight of which phase was formed under varying synthesis conditions. 19F and 207Pb MAS NMR measurements delivered an even further insight into the local structures. Additional simulations of the 19F spectra were performed to identify the 19F-207Pb coupling constants of the four-fold coordinated fluorine sites in both phases.

  4. A Moessbauer effect investigation of superparamagnetic behavior in ball milled Mn-Zn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Dunlap, R.A.; Alghamdi, A.; O' Brien, J.W.; Penney, S.J

    2004-02-25

    Nanostructured Mn{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4}, with x=0.4, 0.5, 0.6 and 0.7, were prepared by ball milling and were investigated using X-ray diffraction and {sup 57}Fe Moessbauer effect methods. Nanocrystallite grain size has been determined from X-ray linewidths to be around 70 A. {sup 57}Fe Moessbauer effect spectra of all samples showed a combination of a ferromagnetic component and a superparamagnetic component. Low-temperature Moessbauer measurements confirmed the identity of the superparamagnetic component and provided mean grain sizes consistent with the X-ray results.

  5. Generation of drugs coated iron nanoparticles through high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Radhika Devi, A.; Murty, B. S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Chelvane, J. A. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh [Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-03-28

    The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

  6. A software tool for simulation of surfaces generated by ball nose end milling

    DEFF Research Database (Denmark)

    Bissacco, Giuliano

    2004-01-01

    The number of models available for prediction of surface topography is very limited. The main reason is that these models cannot be based on engineering principles like those for elastic deformations. Most knowledge about surface roughness and integrity is empirical and up to now very few mathema...... readable by a surface processor software (SPIP [2]), for calculation of a number of surface roughness parameters. In the next paragraph a description of the basic features of ball nose end milled surfaces is given, while in paragraph 3 the model is described....

  7. Dry Grinding Kinetics of Gölbaşı (Ankara Andesite in Ball Mill.

    Directory of Open Access Journals (Sweden)

    T. Agacayak

    2017-01-01

    Full Text Available Kinetic study using a laboratory steel ball mill was carried out to determine dry grinding properties of andesite sample. The Si (specific rate of breakage values were determined by using the single sized feed fractions of - 850+600 µm, -600+425 µm and -425+300 µm. Dry grinding of single size intervals showed that andesite followed the first-order breakage law. The breakage parameters of andesite in terms of the Si, aT and α values were determined.

  8. Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

    Energy Technology Data Exchange (ETDEWEB)

    Lopez B, I.; Trapaga M, L. G. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico); Martinez F, E. [Centro de Investigacion e Innovacion Tecnologica, Cerrada de Cecati s/n, Col. Santa Catarina Azcapotzalco, 02250 Mexico D. F. (Mexico); Zoz, H., E-mail: israelbaez@gmail.co [Zoz GmbH, D-57482, Wenden (Germany)

    2011-07-01

    The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

  9. Raman studies of Ball mill synthesized bulk Cu2ZnSnSe4

    Science.gov (United States)

    Tiwari, Kunal J.; Prem Kumar D., S.; Mallik, Ramesh Chandra; Malar, P.

    2017-05-01

    Kesterite with chemical formula Cu2ZnSnSe4 (CZTSe) has been synthesized by ball milling followed by annealing and hot pressing. Mechanochemical synthesis was carried out in the presence of process control agent namely toluene under two different milling conditions. Structural and phase evolution during different stages of the synthesis was studied with X-ray diffraction (XRD) and Raman spectroscopy. Near resonant Raman spectrum was obtained by making use of laser wavelength of 488 nm to resolve the presence of secondary ZnSe which otherwise is difficult to conclude with XRD alone. Deconvoluted Raman spectrum confirmed the presence of CZTSe along with secondary phases Cu2SnSe3 (CTSe) and ZnSe. This inference was further confirmed by electron probe micro analysis (EPMA) and wavelength dispersive spectroscopy (WDS) studies.

  10. The effects of attrition and ball milling on the properties of magnesium diboride

    Energy Technology Data Exchange (ETDEWEB)

    Dancer, C E J; Crossley, A; Todd, R I; Grovenor, C R M [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Prabhakaran, D, E-mail: claire.dancer@materials.ox.ac.u [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom)

    2010-06-15

    Commercially produced magnesium diboride powder was modified by attrition milling and ball milling in propan-2-ol for various durations. These powders were characterized by means of particle size distribution measurements using laser diffraction, impurity analysis using x-ray diffraction, energy dispersive spectroscopy and x-ray photoelectron spectroscopy, and scanning electron microscopy, and were then used to produce magnesium diboride samples through pressureless heat treatment at peak temperatures up to 1100 {sup 0}C. X-ray diffraction, scanning electron microscopy, Vickers hardness measurements, and density measurements using the Archimedes method were used to characterize the properties of the samples, and a determination of their superconducting properties using the magnetization method was carried out. Magnesium diboride produced from powder milled under certain conditions had a higher J{sub c,mag} than samples produced from as-purchased powder, but the relationship between the milling duration or energy and the superconducting performance is a complex one, affected by both the particle size and the impurity content of the starting powder.

  11. Ultrafine Sm-Fe-N Particles Prepared by Planetary Ball Milling

    Directory of Open Access Journals (Sweden)

    Neil D.

    2013-01-01

    Full Text Available Ultrafine magnetically hard particles are needed for the bottom­up fabrication of anisotropic exchanged­coupled permanent magnets. In this study we have chosen Sm2Fe17Nx because of its high anisotropy field and large saturation magnetization. A multi­stage planetary ball milling process was used. The key is to find the right balance of energy used to mill the precursor particles; it must be high enough to break the particles and reduce their size but, not so high as to destroy the crystal structure of the nanoparticles that would lead to deterioration of the magnetic properties. First the coarse powders were subjected to a wet milling with 2.0 mm diameter media. In each subsequent stage the media size was reduced to maintain the milling balance. Using such a process produced particles in a size range from 100 - 800 nm with a coercivity as high as 10 kOe at room temperature.

  12. Conductometry and Size Characterization of Polypyrrole Nanoparticles Produced by Ball Milling

    Directory of Open Access Journals (Sweden)

    Abdul Malik Rehan Abbasi

    2013-01-01

    Full Text Available Polypyrrole (PPy, one of the most extensively investigated conducting polymers, has attracted a great deal of interest because of its good electrical conductivity, environmental stability, and easy synthesis. PPy films were produced by polymerization of pyrrole and tosylate (TsO− as dopants in the presence of oxidant FeCl3 and polyethylene glycol (Mw 8000 at −5°C for 48 h. High energy milling was carried out at 850 rpm in the dry media with the balls of 10 mm. Particles were then characterized by Scanning Electron Microscope and Dynamic Light Scattering techniques for size distribution, and it was found that the size of PPy particles is a decreasing function of time of milling. Electrical conductivity was measured by preparing a homogenous aqueous dispersion of PPy particles and found as exponential decreasing function of time of milling. The changes occurred in PPy after milling was analyzed by Differential Scanning Calorimetry (DSC and Fourier transform infrared spectroscopy (FTIR.

  13. The development of a ball vibration absorber for the use on towers

    Czech Academy of Sciences Publication Activity Database

    Pirner, Miroš; Fischer, Ondřej

    2000-01-01

    Roč. 41, č. 133 (2000), s. 91-98 ISSN 0304-3622 R&D Projects: GA ČR(CZ) GV103/96/K034 Institutional support: RVO:68378297 Keywords : TV towers * wind-excited vibrations * vibration absorbers * pendulum and ball absorber Subject RIV: JM - Building Engineering http://www.iass-structures.org/index.cfm/journal.issue?iID=33

  14. Ball mill assisted rapid mechanochemical extraction method for natural products from plants.

    Science.gov (United States)

    Wang, Man; Bi, Wentao; Huang, Xiaohua; Chen, David Da Yong

    2016-06-03

    A ball mill assisted mechanochemical extraction method was developed to extract compounds of natural product (NP) from plant using ionic liquid (IL). A small volume ball mill, also known as PastPrep(®) Homogenizer, which is often used for high-speed lysis of biological samples and for other applications, was used to dramatically increase the speed, completeness and reproducibility of the extraction process at room temperature to preserve the chemical integrity of the extracted compounds. In this study, tanshinones were selected as target compounds to evaluate the performance of this extraction method. Factors affecting the extraction efficiency, such as the duration, IL concentration and solid/liquid ratio were systematically optimized using the response surface methodology. Under the optimized conditions, the described method was more efficient and much faster than the conventional extraction methods such as methanol based ultrasound assisted extraction (UAE) and heat reflux extraction (HRE) that consumes a lot more organic solvent. In addition, the natural products of interest were enriched by anion metathesis of ionic liquids, combining extraction and preconcentration in the same process. The extractant was analyzed by HPLC and LC-MS. The reproducibility (RSD, n=5), correlation coefficient (r(2)) of the calibration curve, and the limit of detection, were determined to be in the range of 4.7-5.2%, 0.9992-0.9995, and 20-51ng/mL, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Experimental Investigation into the Effect of Ball End Milling Parameters on Surface Integrity of Inconel 718

    Science.gov (United States)

    Bhopale, Nandkumar N.; Joshi, Suhas S.; Pawade, Raju S.

    2015-02-01

    In machining of Inconel 718, various difficulties such as increased tool wear and poor machined surface quality are frequently encountered due to its high temperature strength and poor thermal properties. This work considers the effect of number of passes and the machining environment on the machined surface quality in ball end milling of Inconel 718, which hitherto has not been adequately understood. To this effect, extensive experimentation has been carried out to analyze machined surface quality and integrity in terms of surface roughness, surface damage, and microhardness variation in the machined surfaces. The machined surfaces show formation of distinct bands as a function of instantaneous machining parameters along the periphery of cutting tool edge. A distinct variation is also observed in the measured values of surface roughness and microhardness in these regions. The minimum surface roughness is obtained in the stable cutting zone and it increases toward the periphery of the cutter on band #2 and band #3. Microhardness of depth beneath the machined surface shows that the machining affected zone varies from 60 to 100 µm in ball end milling under various machining conditions.

  16. Si@SiOx/Graphene Nanosheets Composite: Ball Milling Synthesis and Enhanced Lithium Storage Performance

    Directory of Open Access Journals (Sweden)

    Xiaoyong Tie

    2018-01-01

    Full Text Available Si@SiOx/grapheme nanosheet (Si@SiOx/GNS nanocomposites as high-performance anode materials for lithium-ion batteries are prepared by mechanically blending the mixture of expanded graphite (EG with Si nanoparticles, and characterized by Raman spectrum, X-ray diffraction (XRD, field emission scanning electron microscopy, and transmission electron microscopy. During ball milling process, the size of Si nanoparticles will decrease, and the layer of EG can be peeled off to thin multilayers. Electrochemical tests reveal that the Si@SiOx/GNS nanocomposites show enhanced cycling stability, high reversible capacity, and rate capability, even with high content of active materials of 80% and without electrolyte additives. The retained revisable capacity is 1,055 mAh g−1 after 50 cycles at 0.2 A g−1 and about 63.6% of the initial value. The great electrochemical performance of Si@SiOx/GNS nanocomposites can be ascribed to GNS prepared through heat-treat and ball-milling methods, the decrease in the size of Si nanoparticles and SiOx layer on Si surface, which enhance the interactions between Si and GNS.

  17. Planetary ball milling and supercritical fluid technology as a way to enhance dissolution of bicalutamide.

    Science.gov (United States)

    Szafraniec, Joanna; Antosik, Agata; Knapik-Kowalczuk, Justyna; Kurek, Mateusz; Syrek, Karolina; Chmiel, Krzysztof; Paluch, Marian; Jachowicz, Renata

    2017-11-30

    Dissolution of bicalutamide processed with polyvinylpyrrolidone by either supercritical carbon dioxide or ball milling has been investigated. Various compositions as well as process parameters were used to obtain binary systems of the drug with the carrier. Thermal analysis and powder X-ray diffractometry confirmed amorphization of bicalutamide mechanically activated by ball milling and the decrease in crystallinity of the supercritical carbon dioxide-treated drug. Both methods led to reduction of particles size what was confirmed by scanning electron microscopy and laser diffraction measurements. Moreover, the effect of micronisation was found to depend on the parameters of applied process. Fourier transform infrared spectroscopy revealed the appearance of intermolecular interactions between drug and carrier molecules that play an important role in the stabilization of amorphous form of the active compound. Changes in crystal structure combined with reduced size of particles of bicalutamide dispersed within polymer matrix were found to improve dissolution of bicalutamide by 4 to 10-fold in comparison to untreated drug. It is of particular importance as poor dissolution profiles are considered to be the major limitation in bioavailability of the drug. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. A co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals from ball-milled woods.

    Science.gov (United States)

    Du, Lanxing; Wang, Jinwu; Zhang, Yang; Qi, Chusheng; Wolcott, Michael P; Yu, Zhiming

    2017-08-01

    This study demonstrated the technical potential for the large-scale co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals. Ball-milled woods with two particle sizes were prepared by ball milling for 80min or 120min (BMW80, BMW120) and then enzymatically hydrolyzed. 78.3% cellulose conversion of BMW120 was achieved, which was three times as high as the conversion of BMW80. The hydrolyzed residues (HRs) were neutrally sulfonated cooking. 57.72g/L and 88.16g/L lignosulfonate concentration, respectively, were harvested from HR80 and HR120, and 42.6±0.5% lignin were removed. The subsequent solid residuals were purified to produce cellulose and then this material was acid-hydrolyzed to produce cellulose nanocrystals. The BMW120 maintained smaller particle size and aspect ratio during each step of during the multiple processes, while the average aspect ratio of its cellulose nanocrystals was larger. The crystallinity of both materials increased with each step of wet processing, reaching to 74% for the cellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Characterization of steel 70XL used in the manufacture of balls for the clinker's milling

    Directory of Open Access Journals (Sweden)

    Eider Gresesqui-Lobaina

    2017-10-01

    Full Text Available The present article deals with the wear of the balls used for the grinding of the clinker in the processes of obtaining cement. Three specimens of different steel were made: one of steel AISI 4140, with which balls are forged for the milling process; another 70XL steel (70 XL with normalized, tempered and tempered thermal treatments; and the third, of equal material that the second but without treatment. For the metallographic observation the samples were made with dimensions of 10 mm in diameter and 8 mm in thickness, revealing for AISI 4140 steel a structure of martensitic type with some presence of acicular ferrite. For the 70XL steel without heat treatment the presence of ferrite and cementite was observed, while the steel 70XL with heat treatment showed in the limits of free cementite grain in a pearly matrix, which resulted in a higher hardness (up to HRC 59 , 8 and lower gravimetric wear compared to other materials. Therefore it is recommended as the most suitable for the manufacture of balls for grinding minerals 70XL steel with heat treatment.

  20. Effect of ball to powder ratio on the ZrO{sub 2} phase transformations during milling

    Energy Technology Data Exchange (ETDEWEB)

    Zakeri, M.; Razavi, M., E-mail: m-razavi@merc.ac.ir; Rahimipour, M.R.; Jamal Abbasi, B.

    2014-07-01

    Effect of milling time and ball to powder weight ratio (BPR) were investigated on the phase transformation of monoclinic zirconia during high energy ball milling. Degree of phase transformation was studied by X-ray diffraction (XRD) and quantitative phase analysis (Rietveld refinement). Morphology and microstructure were monitored by scanning and transmission electron microscopy, respectively. Higher milling time and BPR led to the more transformation, smaller mean grain size and larger strain. There was approximately 80% tetragonal zirconia in the 80 h milled powder with the BPR 25:1. A nanostructure powder with the mean grain size less than 10 nm was obtained in both BPRs that were in consistence with TEM images. Stress and strain inducing in the lattice of m-ZrO{sub 2} was proposed as the main mechanism of its transformation.

  1. Niobium Carbide-Reinforced Al Matrix Composites Produced by High-Energy Ball Milling

    Science.gov (United States)

    Travessa, Dilermando Nagle; Silva, Marina Judice; Cardoso, Kátia Regina

    2017-06-01

    Aluminum and its alloys are key materials for the transportation industry as they contribute to the development of lightweight structures. The dispersion of hard ceramic particles in the Al soft matrix can lead to a substantial strengthening effect, resulting in composite materials exhibiting interesting mechanical properties and inspiring their technological use in sectors like the automotive and aerospace industries. Powder metallurgy techniques are attractive to design metal matrix composites, achieving a homogeneous distribution of the reinforcement into the metal matrix. In this work, pure aluminum has been reinforced with particles of niobium carbide (NbC), an extremely hard and stable refractory ceramic. Its use as a reinforcing phase in metal matrix composites has not been deeply explored. Composite powders produced after different milling times, with 10 and 20 vol pct of NbC were produced by high-energy ball milling and characterized by scanning electron microscopy and by X-ray diffraction to establish a relationship between the milling time and size, morphology, and distribution of the particles in the composite powder. Subsequently, an Al/10 pct NbC composite powder was hot extruded into cylindrical bars. The strength of the obtained composite bars is comparable to the commercial high-strength, aeronautical-grade aluminum alloys.

  2. Dioxins reformation and destruction in secondary copper smelting fly ash under ball milling

    Science.gov (United States)

    Cagnetta, Giovanni; Hassan, Mohammed Mansour; Huang, Jun; Yu, Gang; Weber, Roland

    2016-03-01

    Secondary copper recovery is attracting increasing interest because of the growth of copper containing waste including e-waste. The pyrometallurgical treatment in smelters is widely utilized, but it is known to produce waste fluxes containing a number of toxic pollutants due to the large amount of copper involved, which catalyses the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (“dioxins”). Dioxins are generated in secondary copper smelters on fly ash as their major source, resulting in highly contaminated residues. In order to assess the toxicity of this waste, an analysis of dioxin-like compounds was carried out. High levels were detected (79,090 ng TEQ kg-1) in the ash, above the Basel Convention low POPs content (15,000 ng TEQ kg-1) highlighting the hazardousness of this waste. Experimental tests of high energy ball milling with calcium oxide and silica were executed to assess its effectiveness to detoxify such fly ash. Mechanochemical treatment obtained 76% dioxins reduction in 4 h, but longer milling time induced a partial de novo formation of dioxins catalysed by copper. Nevertheless, after 12 h treatment the dioxin content was substantially decreased (85% reduction) and the copper, thanks to the phenomena of incorporation and amorphization that occur during milling, was almost inactivated.

  3. Magnetic and mechanical properties of Cu (75 wt%) – 316L grade stainless steels synthesized by ball milling and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Bholanath, E-mail: bholanath_mondal@yahoo.co.in [Department of Central Scientific Services, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Chabri, Sumit [Department of Metallurgy and Materials Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Sardar, Gargi [Department of Zoology, Baruipur College, South 24 Parganas, 743610 (India); Bhowmik, Nandagopal [Department of Metallurgy and Materials Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Sinha, Arijit, E-mail: arijitsinha2@yahoo.co.in [School of Materials Science and Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Chattopadhyay, Partha Protim [Department of Metallurgy and Materials Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India)

    2015-05-01

    Elemental powders of Cu (75 wt%) and 316-stainless steel (25 wt%) has been subjected to ball milling upto 70 h followed by isothermal annealing at the temperature range of 350–750 °C for 1 h to investigate the microstructural evolution along with magnetic and mechanical properties. After 40 h of milling, the bcc Fe is almost dissolved in the solid solution of Cu but no significant change has been observed in the XRD pattern after 70 h of milling, Annealing of the alloy has resulted in precipitation of nanocrystalline bcc-Fe in Cu which triggers the soft ferromagnetic properties. The extensive mechanical characterization has been done at the microstructural scale by nanoindentation technique which demonstrates a hardening behavior of the compacted and annealed alloys due to possible precipitation of nanocrystalline bcc-Fe in Cu. - Highlights: • Nanocrystalline phases with partial amorphorization obtained after 70 h of milling. • Precipitation and grain coarsening of Fe and Cu after annealing as observed by XRD. • Annealing of the ball milled sample upto 550 {sup o}C has evolved ferromagnetic behavior. • Nanoindentation predicts a hardening behavior of annealed ball milled samples.

  4. Influence of cation disorder on the magnetic properties of ball-milled ilmenite (FeTiO3)

    DEFF Research Database (Denmark)

    Mørup, Steen; Rasmussen, Helge Kildahl; Brok, Erik

    2012-01-01

    We have investigated the evolution of crystal structure, cation disorder and magnetic properties of ilmenite (FeTiO3) after increasing time of high-energy ball-milling in an inert atmosphere. Refinement of X-ray diffraction data show that the hexagonal crystal structure of ilmenite is maintained ...

  5. Structure and thermal stability of nanostructured iron-doped zirconia prepared by high-energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Poulsen, Finn Willy; Mørup, Steen

    1999-01-01

    Fury stability cubic zirconia doped with iron oxide has been synthesized by high-energy ball milling from powder mixtures of monoclinic zirconia and hematite. It is found that the iron ions dissolved in cubic ZrO2 are in substitutional positions with a maximum solubility of approximately 18.5 mol...

  6. Controlling the number of walls in multi walled carbon nanotubes/alumina hybrid compound via ball milling of precipitate catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Nosbi, Norlin [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Akil, Hazizan Md, E-mail: hazizan@usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Cluster for Polymer Composite (CPC), Science and Engineering Research Centre, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia)

    2015-06-15

    Graphical abstract: - Highlights: • We report that, to manipulate carbon nanotubes geometry and number of walls are by controlling the precipitate catalyst size. • Number of walls and geometry effects depend on the milling time of the precipitate catalyst. • Increasing milling of time will decrease the carbon nanotubes number of walls. • Increasing milling of time will increase the carbon nanotubes thermal conductivity. - Abstract: This paper reports the influence of milling time on the structure and properties of the precipitate catalyst of multi walled carbon nanotubes (MWCNT)/alumina hybrid compound, produced through the chemical vapour deposition (CVD) process. For this purpose, light green precipitate consisted of aluminium, nickel(II) nitrate hexahydrate and sodium hydroxide mixture was placed in a planetary mill equipped with alumina vials using alumina balls at 300 rpm rotation speed for various milling time (5–15 h) prior to calcinations and CVD process. The compound was characterized using various techniques. Based on high-resolution transmission electron microscopy analysis, increasing the milling time up to 15 h decreased the diameter of MWCNT from 32.3 to 13.1 nm. It was noticed that the milling time had a significant effect on MWCNT wall thickness, whereby increasing the milling time from 0 to 15 h reduced the number of walls from 29 to 12. It was also interesting to note that the carbon content increased from 23.29 wt.% to 36.37 wt.% with increasing milling time.

  7. Investigation of low-frequency chatter during machining with ball end mills

    Directory of Open Access Journals (Sweden)

    Shtehin O.O.

    2016-12-01

    Full Text Available In this study the investigations of low-frequency oscillations of technological system during machining with ball-end mill of inclined surface were made. An influence of non-linear components of cutting process on change of dynamic state of the system was analyzed. An influence of low-frequency chatter at the beginning of the cutting process on technological system transition to steady state of oscillations with frequencies close to the natural frequency was shown. Explanation of mechanics of transition process from one state to another was proposed. Multiple-factor experiments that included inclined surface machining with different values of spindle speed, allowance, direction of feed motion (upward and downward, cutting patterns (conventional and climb were carried out. Analysis of experimental research showed that downward conventional machining process loses dynamic stability with cutting conditions, for which upward climb machining stays dynamic stable.

  8. Hydrogen storage materials discovery via high throughput ball milling and gas sorption.

    Science.gov (United States)

    Li, Bin; Kaye, Steven S; Riley, Conor; Greenberg, Doron; Galang, Daniel; Bailey, Mark S

    2012-06-11

    The lack of a high capacity hydrogen storage material is a major barrier to the implementation of the hydrogen economy. To accelerate discovery of such materials, we have developed a high-throughput workflow for screening of hydrogen storage materials in which candidate materials are synthesized and characterized via highly parallel ball mills and volumetric gas sorption instruments, respectively. The workflow was used to identify mixed imides with significantly enhanced absorption rates relative to Li2Mg(NH)2. The most promising material, 2LiNH2:MgH2 + 5 atom % LiBH4 + 0.5 atom % La, exhibits the best balance of absorption rate, capacity, and cycle-life, absorbing >4 wt % H2 in 1 h at 120 °C after 11 absorption-desorption cycles.

  9. Comparison on structural modification of industrial lignin by wet ball milling and ionic liquid pretreatment

    Directory of Open Access Journals (Sweden)

    Yongshui Qu

    2015-06-01

    Full Text Available As the most abundant aromatic compounds, lignin is still underutilized due to its relatively low quality. In order to improve its quality, two pretreatment technologies, wet ball milling (WBM and ionic liquid pretreatment (ILP were tested on the industrial lignin and evaluated on the average molecular weight and polydispersity, surface morphology, and functional groups changes. The results showed that the lignin pretreated by the WBM with phosphoric acid presented dramatic decrease of polydipersity (23% and increase of phenolic hydroxyl content (9%. While, the ILP treated samples exhibited the significant reduction of the average molecular weight and polydispersity. The decrease on the particle size and the emergence of the porous structure were found when treated with [Emim][OAc]. In addition, the remarkable reduction of the methoxy groups were observed to be 50% and 45% after treated with [Bmim]Cl and [Emim][OAc], respectively.

  10. Effects of concurrent ball milling and octenyl succinylation on structure and physicochemical properties of starch.

    Science.gov (United States)

    Li, Nannan; Niu, Meng; Zhang, Binjia; Zhao, Siming; Xiong, Shanbai; Xie, Fengwei

    2017-01-02

    This work concerns the effects of concurrent ball milling (BM) and octenyl succinic anhydride (OSA) modification on the starch microstructure and physicochemical properties (swelling, emulsifying, and rheological). Unlike normal OSA-modified starches, the BM/OSA-modified starch displayed new features such as reduced viscosity and rigidity but increased paste stability during shearing, heating and cooling, regardless of the substitution degree. More interestingly, while the physicochemical properties could be regulated by simply altering the BM treatment time, BM/OSA was more efficient and effective at modulating starch properties during the initial period (approx. 10h), as seen by the rapid evolutions in starch structural disruption and OSA esterification. Thus, the BM/OSA modification can serve as a viable and cost-effective approach for producing octenyl succinate starches where low viscosity (at relatively high concentrations) and high paste stability are desired. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Microstructure and low-temperature hydrogen storage capacity of ball-milled graphite

    Energy Technology Data Exchange (ETDEWEB)

    Hentsche, Melanie; Hermann, Helmut; Lindackers, Dirk [Leibniz-Institute for Solid State and Materials Research IFW Dresden, PF 270116, D-01171 Dresden (Germany); Seifert, Gotthard [Technical University Dresden, Institute of Physical Chemistry and Electrochemistry, D-01062 Dresden (Germany)

    2007-07-15

    Hydrogen adsorption in ball-milled graphite is investigated in the low temperature range from 110 to 35 K and at pressures up to 20 MPa. The adsorption data are compared to the results of detailed quantitative microstructural analyses of the samples used for the adsorption experiments. The amount of hydrogen adsorbed at temperatures well below 77 K exceeds considerably that what is expected from adsorption on plane graphitic planes. The results can be explained assuming the following mechanisms: (i) adsorption in trapping states on plane surfaces at and below 110 K; (ii) adsorption in small micropores with diameter of less than 1 nm at 77 K and pressure of 10 MPa, and (iii) multilayer adsorption in mesopores at temperatures from 35 to 40 K and pressure of 2 MPa. The effects observed in the low temperature range are reversible and make the investigated material interesting as a supporting component for liquid hydrogen storage systems. (author)

  12. Fabrication mechanism of FeSe superconductors with high-energy ball milling aided sintering process

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shengnan, E-mail: snzhang@c-nin.com [Northwest Institute for Non-Ferrous Metal Research, 710016, Xi' an (China); Liu, Jixing [Northwest Institute for Non-Ferrous Metal Research, 710016, Xi' an (China); School of Materials and Metallurgical, Northeast University, Shenyang, 110016 (China); Feng, Jianqing; Wang, Yao; Ma, Xiaobo; Li, Chengshan; Zhang, Pingxiang [Northwest Institute for Non-Ferrous Metal Research, 710016, Xi' an (China)

    2015-08-01

    FeSe Superconducting bulks with high content of superconducting PbO-type β-FeSe phase were prepared with high-energy ball milling (HEBM) aided sintering process. During this process, precursor powders with certain Fe/Se ratio were ball milled first then sintered. The influences of HEBM process as well as initial Fe/Se ratio on the phase evolution process were systematically discussed. With HEBM process and proper initial Fe/Se ratio, the formation of non-superconducting hexagonal δ-FeSe phase were effectively avoided. FeSe bulk with the critical temperature of 9.0 K was obtained through a simple one-step sintering process with lower sintering temperature. Meanwhile, the phase evolution mechanism of the HEBM precursor powders during sintering was deduced based on both the thermodynamic analysis and step-by-step sintering results. The key function of the HEBM process was to provide a high uniformity of chemical composition distribution, thus to successfully avoide the formation of intermediate product during sintering, including FeSe{sub 2} and Fe{sub 7}Se{sub 8}. Therefore, the fundamental principal for the synthesis of FeSe superconductors were concluded as: HEBM aided sintering process, with the sintering temperature of >635 °C and a slow cooling process. - Highlights: • A novel synthesis technique was developed for FeSe based superconductors. • FeSe bulks with high Tc and high β-FeSe phase content has been obtained. • Phase evolution process for the HEBM aided sintering process was proposed.

  13. Easily recycled Bi2O3 photocatalyst coatings prepared via ball milling followed by calcination

    Science.gov (United States)

    Cheng, Lijun; Hu, Xumin; Hao, Liang

    2017-06-01

    Bi2O3 photocatalyst coatings derived from Bi coatings were first prepared by a two-step method, namely ball milling followed by the calcination process. The as-prepared samples were characterized by XRD, SEM, XPS and UV-Vis spectra, respectively. The results showed that monoclinic Bi2O3 coatings were obtained after sintering Bi coatings at 673 or 773 K, while monoclinic and triclinic mixed phase Bi2O3 coatings were obtained at 873 or 973 K. The topographies of the samples were observably different, which varied from flower-like, irregular, polygonal to nanosized particles with the increase in calcination temperature. Photodegradation of malachite green under simulated solar irradiation for 180 min showed that the largest degradation efficiency of 86.2% was achieved over Bi2O3 photocatalyst coatings sintered at 873 K. The Bi2O3 photocatalyst coatings, encapsulated with Al2O3 ball with an average diameter around 1 mm, are quite easily recycled, which provides an alternative visible light-driven photocatalyst suitable for practical water treatment application.

  14. A combination method of the theory and experiment in determination of cutting force coefficients in ball-end mill processes

    Directory of Open Access Journals (Sweden)

    Yung-Chou Kao

    2015-10-01

    Full Text Available In this paper, the cutting force calculation of ball-end mill processing was modeled mathematically. All derivations of cutting forces were directly based on the tangential, radial, and axial cutting force components. In the developed mathematical model of cutting forces, the relationship of average cutting force and the feed per flute was characterized as a linear function. The cutting force coefficient model was formulated by a function of average cutting force and other parameters such as cutter geometry, cutting conditions, and so on. An experimental method was proposed based on the stable milling condition to estimate the cutting force coefficients for ball-end mill. This method could be applied for each pair of tool and workpiece. The developed cutting force model has been successfully verified experimentally with very promising results.

  15. Carbon Nanotube-Reinforced Aluminum Matrix Composites Produced by High-Energy Ball Milling

    Science.gov (United States)

    Travessa, Dilermando N.; da Rocha, Geovana V. B.; Cardoso, Kátia R.; Lieblich, Marcela

    2017-05-01

    Although multiwall carbon nanotubes (MWCNT) are promising materials to strengthen lightweight aluminum matrix composites, their dispersion into the metallic matrix is challenge. In the present work, MWCNT were dispersed into age-hardenable AA6061 aluminum alloy by high-energy ball milling and the blend was subsequently hot-extruded. The composite bars obtained were heat-treated by solution heat treatment at 520 °C and artificially aged at 177 °C for 8 h, in order to reach the T6 temper. Special attention was given to the integrity of the MWCNT along the entire composite production. The microstructure of the obtained bars was evaluated by optical and scanning electron microscopy, and the mechanical properties were evaluated by Vickers microhardness tests. Raman spectroscopy, x-ray diffraction and transmission electron microscopy were employed to evaluate the structural integrity of MWCNT. It was found that milling time is critical to reach a proper dispersion of the reinforcing phase. The composite hardness increased up to 67% with the dispersion of 2% in weight of MWCNT, when comparing with un-reinforced bars produced by similar route. However, age hardening was not observed in composite bars after heat treatment. It was also found that MWCNT continuously degraded along the process, being partially converted into Al4C3 in the final composite.

  16. On the amorphization behavior and hydrogenation performance of high-energy ball-milled Mg{sub 2}Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kou, Hongchao; Hou, Xiaojiang; Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Hu, Rui; Li, Jinshan; Xue, Xiangyi

    2013-06-15

    Amorphous Mg{sub 2}Ni alloy was prepared by high energy ball-milling starting with polycrystalline Mg{sub 2}Ni which was prepared with the help of a metallurgy method by using a SPEX 8000D mill. The microstructural and phase structure characterization of the prepared materials was performed via scanning electron microscopy, transition electron microscope and X-ray diffraction. The thermal stabilities were investigated by differential scanning calorimetry. The apparent activation energies were determined by means of the Kissinger method. The first and second crystallization reactions take place at ∼ 255 °C and ∼ 410 °C, and the corresponding activation energy of crystallization is E{sub a1} = 276.9 and E{sub a2} = 382.4 kJ/mol, respectively. At 3 MPa hydrogen pressure and 250 °C, the hydrogen absorption capacities of crystalline, partially and fully amorphous Mg{sub 2}Ni alloy are 2.0 wt.%, 3.2 wt.% and 3.5 wt.% within 30 min, respectively. - Graphical Abstract: We mainly focus on the amorphization behavior of crystalline Mg{sub 2}Ni alloy in the high energy ball-milling process and the crystallization behavior of the amorphous Mg{sub 2}Ni alloy in a follow-up heating process. The relationship of milling, microstructure and hydrogenation properties is established and explained by models. - Highlights: • Amorphous Mg{sub 2}Ni has been obtained by high energy ball milling the as-cast alloy. • The amorphization behavior of polycrystalline Mg{sub 2}Ni is presented. • The crystallization behavior of the amorphous Mg{sub 2}Ni alloy is illustrated. • Establish the relationship of milling, microstructure and hydrogenation properties.

  17. Synthesis and characterization of FePt nanoparticles by high energy ball milling with and without surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Velasco, V., E-mail: vvjimeno@fis.ucm.es [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Martinez, A.; Recio, J. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Hernando, A.; Crespo, P. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Dpto. de Fisica de Materiales, UCM, 28040 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Fe and Pt powders in the presence of surfactants don't alloyed by HEBM technique. Black-Right-Pointing-Pointer FePt alloys obtained by dry milling exhibit particle sizes of around 10 {mu}m. Black-Right-Pointing-Pointer FePt alloys obtained by dry milling exhibit soft magnetic behavior. Black-Right-Pointing-Pointer A thermal treatment induces a phase transformation from FCC to FCT. - Abstract: FePt nanoparticles were prepared by high energy ball milling (HEBM) in two different ways. In the first one, elemental powders were mixed and milled whereas in the second one the milling was performed in the presence of oleyl amine and oleic acid as surfactants and hexane as a solvent. X-ray diffraction shows that when the milling is performed in dry conditions, Fe and Pt are alloyed after 5 h, whereas in the wet milling procedure alloying does not take place. In the first case, the diffraction pattern corresponds to the disordered FCC phase. This behavior is also corroborated by the evolution of the magnetic characteristics. In the case of the alloy obtained in dry conditions, the powder was heat treated in order to induce the transformation to the ordered phase. Coercivities of 2.5 kOe are obtained after 650 Degree-Sign C for 2 h.

  18. Structural Investigations of TiC–Cu Nanocomposites Prepared by Ball Milling and Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Hoang ,Oanh

    2017-04-01

    Full Text Available In this work, TiC–Cu composites containing 20 and 30 vol % of nano-sized titanium carbide (TiC particles were prepared by powder metallurgy using copper powders with micrometer-sized and nanometer-sized particles. Mixtures of TiC and Cu powders were ball milled for 10 h and spark plasma sintered at 800–900 °C under an applied pressure of 50 MPa. The relative density of the sintered composites was 95.0%–96.5%. The composites fractured in a ductile mode. The crystallite size of the copper matrix in the composites prepared using the nanometer-sized copper powder was smaller than that in composites prepared using the micrometer-sized copper powder, which was confirmed by transmission electron microscopy (TEM. The hardness of the composites increased as the sintering temperature was increased from 800 to 900 °C. When the TiC content increased from 20 to 30 vol %, the hardness of the composites obtained from the micrometer-sized copper powder and sintered at 900 °C increased from 284 to 315 HV, while in composites obtained from the nanometer-sized copper, the hardness decreased from 347 to 337 HV.

  19. Drawing Sensors with Ball-Milled Blends of Metal-Organic Frameworks and Graphite.

    Science.gov (United States)

    Ko, Michael; Aykanat, Aylin; Smith, Merry K; Mirica, Katherine A

    2017-09-23

    The synthetically tunable properties and intrinsic porosity of conductive metal-organic frameworks (MOFs) make them promising materials for transducing selective interactions with gaseous analytes in an electrically addressable platform. Consequently, conductive MOFs are valuable functional materials with high potential utility in chemical detection. The implementation of these materials, however, is limited by the available methods for device incorporation due to their poor solubility and moderate electrical conductivity. This manuscript describes a straightforward method for the integration of moderately conductive MOFs into chemiresistive sensors by mechanical abrasion. To improve electrical contacts, blends of MOFs with graphite were generated using a solvent-free ball-milling procedure. While most bulk powders of pure conductive MOFs were difficult to integrate into devices directly via mechanical abrasion, the compressed solid-state MOF/graphite blends were easily abraded onto the surface of paper substrates equipped with gold electrodes to generate functional sensors. This method was used to prepare an array of chemiresistors, from four conductive MOFs, capable of detecting and differentiating NH₃, H₂S and NO at parts-per-million concentrations.

  20. Insertion compounds and composites made by ball milling for advanced sodium-ion batteries.

    Science.gov (United States)

    Zhang, Biao; Dugas, Romain; Rousse, Gwenaelle; Rozier, Patrick; Abakumov, Artem M; Tarascon, Jean-Marie

    2016-01-18

    Sodium-ion batteries have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. However, their future commercialization depends critically on control over the solid electrolyte interface formation, as well as the degree of sodiation at the positive electrode. Here we report an easily scalable ball milling approach, which relies on the use of metallic sodium, to prepare a variety of sodium-based alloys, insertion layered oxides and polyanionic compounds having sodium in excess such as the Na4V2(PO4)2F3 phase. The practical benefits of preparing sodium-enriched positive electrodes as reservoirs to compensate for sodium loss during solid electrolyte interphase formation are demonstrated by assembling full C/P'2-Na1[Fe0.5Mn0.5]O2 and C/'Na3+xV2(PO4)2F3' sodium-ion cells that show substantial increases (>10%) in energy storage density. Our findings may offer electrode design principles for accelerating the development of the sodium-ion technology.

  1. Magnetism of fine particles of Kondo lattices, obtained by high-energy ball-milling.

    Science.gov (United States)

    Sampathkumaran, E V; Mukherjee, K; Iyer, Kartik K; Mohapatra, Niharika; Das, Sitikantha D

    2011-03-09

    Despite intense research in the field of strongly correlated electron behavior for the past few decades, there has been very little effort to understand this phenomenon in nanoparticles of the Kondo lattices. In this paper, we review the results of our investigation on the fine particles (high-energy ball-milling, to bring out that this synthetic method paves a way to study strong electron correlations in nanocrystals of such alloys. We primarily focus on the alloys of the series CeRu(2 - x)Rh(x)Si2, lying at different positions in Doniach's magnetic phase diagram. While CeRu2Si2, a bulk paramagnet, appears to become magnetic (of a glassy type) below about 8 K in fine particle form, in CeRh2Si2, an antiferromagnet (T(N) = 36 K) in bulk form, magnetism is destroyed (at least down to 0.5 K) in fine particles. In the alloy CeRu0.8Rh1.2Si2, at the quantum critical point known to exhibit non-Fermi liquid behavior in the bulk form, no long range magnetic ordering is found.

  2. Drawing Sensors with Ball-Milled Blends of Metal-Organic Frameworks and Graphite

    Science.gov (United States)

    Ko, Michael; Aykanat, Aylin; Smith, Merry K.

    2017-01-01

    The synthetically tunable properties and intrinsic porosity of conductive metal-organic frameworks (MOFs) make them promising materials for transducing selective interactions with gaseous analytes in an electrically addressable platform. Consequently, conductive MOFs are valuable functional materials with high potential utility in chemical detection. The implementation of these materials, however, is limited by the available methods for device incorporation due to their poor solubility and moderate electrical conductivity. This manuscript describes a straightforward method for the integration of moderately conductive MOFs into chemiresistive sensors by mechanical abrasion. To improve electrical contacts, blends of MOFs with graphite were generated using a solvent-free ball-milling procedure. While most bulk powders of pure conductive MOFs were difficult to integrate into devices directly via mechanical abrasion, the compressed solid-state MOF/graphite blends were easily abraded onto the surface of paper substrates equipped with gold electrodes to generate functional sensors. This method was used to prepare an array of chemiresistors, from four conductive MOFs, capable of detecting and differentiating NH3, H2S and NO at parts-per-million concentrations. PMID:28946624

  3. High-speed vibration-milling-promoted synthesis of symmetrical frameworks containing two or three pyrrole units

    Directory of Open Access Journals (Sweden)

    Marco Leonardi

    2017-09-01

    Full Text Available The pseudo-five-component reaction between β-dicarbonyl compounds (2 molecules, diamines and α-iodoketones (2 molecules, prepared in situ from aryl ketones, was performed efficiently under mechanochemical conditions involving high-speed vibration milling with a single zirconium oxide ball. This reaction afforded symmetrical frameworks containing two pyrrole or fused pyrrole units joined by a spacer, which are of interest in the exploration of chemical space for drug discovery purposes. The method was also extended to the synthesis of one compound containing three identical pyrrole fragments via a pseudo-seven-component reaction. Access to compounds having a double bond in their spacer chain was achieved by a different approach involving the homodimerization of 1-allyl- or 1-homoallylpyrroles by application of cross-metathesis chemistry.

  4. Impact Analysis of Roller System Stability for Four-High Mill Horizontal Vibration

    Directory of Open Access Journals (Sweden)

    Xiao-bin Fan

    2016-01-01

    Full Text Available In order to study the hot Compact Strip Production (CSP, four-high mill vibration characteristics, and vibration suppression method, the roller system structure stability was analyzed and calculated at first in the paper. And then, the mill stand gap was measured at field and its influence on roll transverse vibration was analyzed. The drum gear coupling effect on the roller system stability and the automatic balance conditions of the coupling transmission torque were studied; the influence of axial force caused by the roller cross on the system stability was analyzed. Finally, the roller transverse friction chatter vibration mechanics model was established; the simulation analysis was carried out with eliminating mill house-bearing clearance and adding floating support for coupling, respectively. And the characteristics of the roller “jump vibration” were studied. We applied copper gaskets to eliminate or reduce mill house-bearing clearance for suppressing the rolling mill vibration on the spot; the test results show that the roller transverse vibration was suppressed after eliminating clearance.

  5. Integrated modeling and analysis of ball screw feed system and milling process with consideration of multi-excitation effect

    Science.gov (United States)

    Zhang, Xing; Zhang, Jun; Zhang, Wei; Liang, Tao; Liu, Hui; Zhao, Wanhua

    2018-01-01

    The present researches about feed drive system and milling process are almost independent with each other, and ignore the interaction between the two parts, especially the influence of nonideal motion of feed drive system on milling process. An integrated modeling method of ball screw feed system and milling process with multi-excitation effect is proposed in this paper. In the integrated model, firstly an analytical model of motor harmonic torque with consideration of asymmetrical drive circuit and asymmetrical permanent magnet is given. Then, the numerical simulation procedure of cutter/workpiece engagement during milling process with displacement fluctuation induced by harmonic torque is put forward, which is followed by the solving flow for the proposed integrated model. Based on the integrated model, a new kind of quality defect shown as contour low frequency oscillation on machined surface is studied by experiments and simulations. The results demonstrate that the forming mechanism of the contour oscillation can be ascribed to the multi-excitation effect with motor harmonic torque and milling force. Moreover, the influence of different milling conditions on the contour oscillation characteristics, particularly on surface roughness, are further discussed. The results indicate that it is necessary to explain the cause of the new kind of quality defect with a view of system integration.

  6. Effect of process variables on synthesis of MgB2 by a high energy ball mill

    Directory of Open Access Journals (Sweden)

    Kurama Haldun

    2016-01-01

    Full Text Available The discovery of superconductivity of MgB2 in 2001, with a critical temperature of 39 K, offered the promise of important large-scale applications at around 20 K. Except than the other featured synthesis methods, mechanical activation performed by high energy ball mills, as bulk form synthesis or as a first step of wire and thin film productions, has considered as an effective alternative production route in recent years. The process of mechanical activation (MA starts with mixing the powders in the right proportion and loading the powder mixture into the mill with the grinding media. The milled powder is then consolidated into a bulk shape and heat-treated to obtain desired microstructure and properties. Thus, the important components of the MA process are the raw materials, mill type and process variables. During the MA process, heavy deformation of particles occure. This is manifested by the presence of a variety of crystal defects such as dislocations, vacancies, stacking faults and increased number of particle boundaries. The presence of this defect structure enhances the diffusivity of solute hence the critical currents and magnetic flux pinning ability of MgB2 are improved. The aim of the present study is to determine the effects of process variables such as ball-to-powder mass ratio, size of balls, milling time, annealing temperature and contribution of process control agent (toluene on the product size, morphology and conversion level of precursor powders to MgB2 after subsequent heat treatment. The morphological analyses of the samples were performed by a high vacuum electron microscope ZEISS SUPRA VP 50. The phase compositions of the samples were performed with an Rigaku-Rint 2200 diffractometer, with nickel filtered Cu Kα radiation and conversion level. The MgB2 phase wt % was calculated by the Rietveld refinement method. The obtained results were discussed according to the process variables to find out their affect on the structure

  7. Investigation of griseofulvin and hydroxypropylmethyl cellulose acetate succinate miscibility in ball milled solid dispersions.

    Science.gov (United States)

    Al-Obaidi, Hisham; Lawrence, M Jayne; Al-Saden, Noor; Ke, Peng

    2013-02-25

    Solid dispersions of varying weight ratios compositions of the nonionic drug, griseofulvin and the hydrophilic, anionic polymer, hydroxylpropylmethyl cellulose acetate succinate, have been prepared by ball milling and the resulting samples characterized using a combination of Fourier transform infra-red spectroscopy, X-ray powder diffraction and differential scanning calorimetry. The results suggest that griseofulvin forms hydrogen bonds with the hydroxylpropylmethyl cellulose acetate succinate polymer when prepared in the form of a solid dispersion but not when prepared in a physical mixture of the same composition. As anticipated, the actual measured glass transition temperature of the solid dispersions displayed a linear relationship between that predicted using the Gordon-Taylor and Fox equations assuming ideal mixing, but interestingly only at griseofulvin contents less than 50 wt%. At griseofulvin concentrations greater than this, the measured glass transition temperature of the solid dispersions was almost constant. Furthermore, the crystalline content of the solid dispersions, as determined by differential scanning calorimetry and X-ray powder diffraction followed a similar trend in that the crystalline content significantly decreased at ratios less than 50 wt% of griseofulvin. When the physical mixtures of griseofulvin and the hydroxylpropylmethyl cellulose acetate succinate polymer were analyzed using the Flory-Huggins model, a negative free energy of mixing with an interaction parameter of -0.23 were obtained. Taken together these results suggest that anionic hydrophilic hydroxylpropylmethyl cellulose acetate succinate polymer is a good solvent for crystalline nonionic griseofulvin with the solubility of griseofulvin in the solid dispersion being was estimated to be within the range 40-50 wt%. Below this solubility limit, the amorphous drug exists as amorphous glassy solution while above these values the system is supersaturated and glassy suspension and

  8. Modified inelastic bouncing ball model for describing the dynamics of granular materials in a vibrated container

    Science.gov (United States)

    Balista, Junius André F.; Saloma, Caesar

    2015-01-01

    We show that at the onset of convection, the acceleration of a confined granular material is not necessarily equal to that of its vibrated container. Convection happens when the material is able to counter the downward gravitational pull and accelerates at a rate that is equal to the gravitational acceleration g. We modify the Inelastic Bouncing Ball Model and incorporate the transmissibility parameter Tr which measures the efficiency that the external force driving the container is transmitted to the material itself. For a specified Tr value, the material is represented by an inelastic bouncing ball with a time-of-flight T(Γ ;Tr) where Γ =A0ω2 / g, is the dimensionless container acceleration, and A0 and ω are the driving amplitude and angular frequency, respectively. For a given Γ-range, the T(Γ ;Tr) curve provides the bifurcation diagram of the perturbed material and a family of bifurcation diagrams is generated for a set of Tr values. We illustrate that Tr is useful in rationalizing experimental results produced by confined granular materials that is subjected to a range of applied force magnitudes. For the same physical set-up, the force transmission efficiency from the container to the grains may not remain constant as the force strength is varied. The efficiency is also affected by the presence or absence of air in the vibrated container.

  9. Preparation of ultrafine magnetic biochar and activated carbon for pharmaceutical adsorption and subsequent degradation by ball milling

    Science.gov (United States)

    Shan, Danna; Deng, Shubo; Zhao, Tianning; Wang, Bin; Wang, Yujue; Huang, Jun; Yu, Gang; Winglee, Judy; Wiesner, Mark R.

    2017-01-01

    Ball milling was used to prepare two ultrafine magnetic biochar/Fe3O4 and activated carbon (AC)/Fe3O4 hybrid materials targeted for use in pharmaceutical removal by adsorption and mechanochemical degradation of pharmaceutical compounds. Both hybrid adsorbents prepared after 2 hours milling exhibited high removal of carbamazepine (CBZ), and were easily separated magnetically. These adsorbents exhibited fast adsorption of CBZ and tetracycline (TC) in the initial 1 hour. The biochar/Fe3O4 had a maximum adsorption capacity of 62.7 mg/g for CBZ and 94.2 mg/g for TC, while values obtained for AC/Fe3O4 were 135.1 mg/g for CBZ and 45.3 mg/g for TC respectively when data were fitted using the Langmuir expression. Solution pH values slightly affected the sorption of TC on the adsorbents, while CBZ sorption was almost pH-independent. The spent adsorbents with adsorbed CBZ and TC were milled to degrade the adsorbed pollutants. The adsorbed TC itself was over 97% degraded after 3 hours of milling, while about half of adsorbed CBZ were remained. The addition of quartz sand was found to improve the mechanochemical degradation of CBZ on biochar/Fe3O4, and its degradation percent was up to 98.4% at the dose of 0.3 g quarts sand/g adsorbent. This research provided an easy method to prepare ultrafine magnetic adsorbents for the effective removal of typical pharmaceuticals from water or wastewater and degrade them using ball milling. PMID:26685062

  10. Preparation of bismuth telluride based thermoelectric nanomaterials via low-energy ball milling and their property characterizations

    Science.gov (United States)

    Robinson, Christopher A.

    Thermoelectric materials are able to convert energy between heat and electricity with no moving parts, making them very appealing for power generation purposes. This is particularly appealing since many forms of energy generation lose energy to waste heat. The Livermore National Laboratory estimates that up to 55% of the energy created in traditional power plants is lost through heat generation [1]. As greenhouse gas emissions become a more important issue, large sources of waste like this will need to be harnessed. Adoption of these materials has been limited due to the cost and efficiency of current technology. Bismuth telluride based alloys have a dimensionless figure of merit, a measure of efficiency, near one at room temperature, which makes it the best current material. In order to compete with other forms of energy generation, this needs to be increased to three or higher [2]. Recently, improvements in performance have come in the form of random nanostructured materials [3]. Bulk bismuth telluride is subjected to particle size reduction via high-energy ball milling in order to scatter phonons between grains. This reduces the lattice thermal conductivity which in turn increases the performance of the material. In this work, we investigate the use of low-energy ball milling as a method of creating nanoparticles of n-type and p-type Bi2Te3 alloys for thermoelectric applications. Optimization of parameters such as milling containers, milling media, contamination and milling time has resulted in creating 15nm particles of bismuth telluride alloys. After creating solid pellets of the resulting powders via hot pressing, the material's thermal and electrical conductivities as well as Seebeck coefficients were measured. The ZT of n-type Bi2Te2.7Se3 created using this method is 0.32, while the p-type Bi0.5Sb1.5Te3 exhibits a higher ZT of 1.24, both at room temperature.

  11. Vibration analysis of angular contact ball bearing operated with copper oxide nanoparticles mixed ISO VG 68 lubricating oil

    Directory of Open Access Journals (Sweden)

    Prakash E.

    2014-09-01

    Full Text Available The purpose of this paper is to investigate the effect of CuO nanoparticles on lubricating oil and vibration reduction in angular contact ball bearing. CuO nanoparticles are synthesized by using chemical method and characteristic studies done in XRD and TEM. CuO nanoparticles size achieved in the range 26 - 30 nm. The nanoparticles concentration of 0.2 wt. % added into the lubricant (ISO VG 68. The testrig setup consists of angular contact ball bearing operated by AC motor with speed controller. The bearing (New and outer defect vibrations measured using base oil and CuO mixed oil.

  12. Study on residual stresses in ultrasonic torsional vibration assisted micro-milling

    Science.gov (United States)

    Lu, Zesheng; Hu, Haijun; Sun, Yazhou; Sun, Qing

    2010-10-01

    It is well known that machining induced residual stresses can seriously affect the dimensional accuracy, corrosion and wear resistance, etc., and further influence the longevity and reliability of Micro-Optical Components (MOC). In Ultrasonic Torsional Vibration Assisted Micro-milling (UTVAM), cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank are the main factors which affect residual stresses. A 2D model of UTVAM was established with FE analysis software ABAQUS. Johnson-Cook's flow stress model and shear failure principle are used as the workpiece material model and failure principle, while friction between tool and workpiece uses modified Coulomb's law whose sliding friction area is combined with sticking friction. By means of FEA, the influence rules of cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank on residual stresses are obtained, which provides a basis for choosing optimal process parameters and improving the longevity and reliability of MOC.

  13. Research on cutting vibration characteristics of face-milling involute gear

    Directory of Open Access Journals (Sweden)

    Chengzhe JIN

    2017-10-01

    Full Text Available Traditional machining methods, such as gear hobbing, gear shaping and gear milling, etc, are commonly used for cutting machining of gear tooth profile, which cannot meet huge machining demand of gears to a certain extent. This article proposes to utilize a face-milling machining method in involute gear machining, which can be used to reduce production cost effectively. Cutting vibration generated during cutting machining has a direct effect on the machining accuracy and machined surface quality of workpiece. Therefore, it is desiderated to perform in-depth research regarding this issue. ADAMS software was used to establish a rigid-flexible coupling virtual prototyping model of face-milling gear milling system and a cutting vibration system model. Cutting vibration analysis was performed for face-milling gear by adopting quick sine frequency sweep method, so that the frequency response characteristics of workpiece in three directions X, Y and Z and space were acquired. The research results will provide reference and theoretical foundation for actual application of face-milling gear machining technology.

  14. Simulation of Vibrations in Real Time Plane Milling with Spindle Speed Correction

    Directory of Open Access Journals (Sweden)

    I. I. Ivanov

    2017-01-01

    Full Text Available In milling the hard-to-machine materials vibrations (chatter often arise from the high cutting forces if a technological system is insufficiently rigid.The main way to suppress these vibrations is to increase a stiffness of the mounting system of the tool and the work-piece to be machined. However, sometimes this method doesn’t lead to desirable result because of high values of intrinsic pliability of the tool and the work-piece. Currently, there are more complicated methods to ensure milling process quality. Among them there are three main groups:mathematical simulation of milling process dynamics and computation of processing parameters which provide high quality of machined surface, low level of vibrations and static deflections of a tool and a work-piece;introduction of the active vibration suppression devices into machine tool design; such devices include a vibration sensor, a feedback circuit, and an actuator which induces kinematic or force action on the oscillatory system;control of processing parameters, mainly of rotation frequency for minimizing the amplitudes of vibrations.The paper studies one of the 3rd group methods. There is a suggestion to process a signal of vibrational accelerations in real time and detect a chatter onset. If the chatter has been detected its frequency is to be identified, and the new value of rotation speed is set:where Ω – rotation frequency, rot/s; p – the tool eigenfrequency value identified during processing, Hz; z – mill tooth number; i – positive integer number; ε<1 – small positive parameter. In the current research it is assumed that ε = 0,2.The formula has been chosen because at the rotation frequency axis where tooth pass frequency is slightly less than the eigenfrequency divided by the integer value there are stable zones of dynamics in the milling process.The study shows a developed model of the plane milling dynamics. It includes a dynamic model of the tool, a model of cutting

  15. Improved critical current densities in bulk FeSe superconductor using ball milled powders and high temperature sintering

    Energy Technology Data Exchange (ETDEWEB)

    Muralidhar, M.; Furutani, K.; Murakami, M. [Graduate School of Science and Engineering, Superconducting Materials Laboratory, Shibaura Institute of Technology, Tokyo (Japan); Kumar, Dinesh; Rao, M.S. Ramachandra [Department of Physics, Nano Functional Materials Technology Centre and Materials Science Research Centre, Indian Institute of Technology Madras, Chennai (India); Koblischka, M.R. [Institute of Experimental Physics, Saarland University, Saarbruecken (Germany)

    2016-12-15

    The present study is investigating the effect of high temperature sintering combined with ball milled powders for the preparation of FeSe material via solid state sintering technique. The commercial powders of Fe (99.9% purity) and Se (99.9% purity) were mixed in a nominal ratio Fe:Se = 1:1 and thoroughly ground and ball-milled in a glove box during 6 h. Then, the powder mixture was pressed into pellets of 5 mm in diameter and 2 mm thickness using an uniaxial pressure of 100 MPa. The samples were sealed in quartz tubes and sintered at 600 C for 24 h. Then, the pellets were again thoroughly ground and ball-milled in the glove box and pressed into pellets, and the final sintering was performed at two different temperatures, namely at 900 C for 24 h and at 950 C for 24 h. X-ray diffraction results confirmed that both samples showed mainly of the β-FeSe with tetragonal structure. The temperature dependence of magnetization (M-T) curves revealed a sharp superconducting transition T{sub c,} {sub onset} = 8.16 K for the sample sintered at 900 C. Further, scanning electron microscopy observations proved that samples sintered at 900 C show a platelike grain structure with high density. As a result, improved irreversibility fields around 5 T and the critical current density (J{sub c}) values of 6252 A cm{sup -2} at 5 K and self-field are obtained. Furthermore, the normalized volume pinning force versus the reduced field plots indicated a peak position at 0.4 for the sample sintered at 900 C. Improved flux pinning and the high J{sub c} values are attributed to the textured microstructure of the material, produced by a combination of high temperature sintering and ball milling. (copyright 2016 The Authors. Phys. Status Solidi A published by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Prediction of cutting forces in ball-end milling of 2.5D C/C composites

    Directory of Open Access Journals (Sweden)

    Shan Chenwei

    2016-06-01

    Full Text Available Machining of carbon/carbon (C/C composite materials is difficult to carry out due to its high specific stiffness, brittleness, anisotropic, non-homogeneous and low thermal conductivity, which can result in tear, burr, poor surface quality and rapid wear of cutters. Accurate and fast prediction of cutting forces is important for milling C/C composite materials with high quality. This paper presents an alternative cutting force model involving the influences of the directions of fiber. Based on the calculated and experimental results, the cutting forces’ coefficients of 2.5D C/C composites are evaluated using multiple linear regression method. Verification experiment has been carried out through a group of orthogonal tests. Results indicate that the proposed model is reliable and can be used to predict the cutting forces in ball-end milling of 2.5D C/C composites.

  17. Influence of emulsifiers on the optimization of processing parameters of refining milk chocolate in the ball mill

    Directory of Open Access Journals (Sweden)

    Pajin Biljana

    2011-01-01

    Full Text Available Chocolate manufacture is a complex process which includes a large number of technology operations. One of the obligatory phases is milling, called refining, which aims at obtaining the appropriate distribution of particle size, resulting in the chocolate with optimal physical and sensory characteristics. The aim of this work was to define and optimize the process parameters for the production of milk chocolate by a non-conventional procedure, using the ball mill. The quality of chocolate mass, produced on this way, is determined by measuring the following parameters: moisture, size of the largest cocoa particle, yield flow, and Casson plastic viscosity. A special consideration of this study is the optimization of the types and amounts of emulsifiers, which are responsible for achieving the appropriate rheological and physical characteristics of the chocolate mass. The obtained parameters are compared with those which are typical for the standard procedure.

  18. Enhanced lithium storage in ZnFe2O4-C nanocomposite produced by a low-energy ball milling

    Science.gov (United States)

    Thankachan, Rahul Mundiyaniyil; Rahman, Md Mokhlesur; Sultana, Irin; Glushenkov, Alexey M.; Thomas, Sabu; Kalarikkal, Nandakumar; Chen, Ying

    2015-05-01

    Preparation of novel nanocomposite structure of ZnFe2O4-C is achieved by combining a sol-gel and a low energy ball milling method. The crucial feature of the composite's structure is that sol-gel synthesised ZnFe2O4 nanoparticles are dispersed and attached uniformly along the chains of Super P Li™ carbon black matrix by adopting a low energy ball milling. The composite ZnFe2O4-C electrodes are capable of delivering a very stable reversible capacity of 681 mAh g-1 (96% retention of the calculated theoretical capacity of ∼710 mAh g-1) at 0.1 C after 100 cycles with a remarkable Coulombic efficiency (82%) improvement in the first cycle. The rate capability of the composite is significantly improved and obtained capacity was as high as 702 at 0.1, 648 at 0.5, 582 at 1, 547 at 2 and 469 mAh g-1 at 4 C (2.85 A g-1), respectively. When cell is returned to 0.1 C, the capacity recovery was still ∼98%. Overall, the electrochemical performance (in terms of cycling stability, high rate capability, and capacity retention) is outstanding and much better than those of the related reported works. Therefore, our smart electrode design enables ZnFe2O4-C sample to be a high quality anode material for lithium-ion batteries.

  19. Impact of high energy ball milling on the nanostructure of magnetite–graphite and magnetite–graphite–molybdenum disulphide blends

    Energy Technology Data Exchange (ETDEWEB)

    Österle, W., E-mail: Werner.oesterle@bam.de [BAM Federal Institute for Materials Research and Testing, 12200 Berlin (Germany); Orts-Gil, G.; Gross, T.; Deutsch, C. [BAM Federal Institute for Materials Research and Testing, 12200 Berlin (Germany); Hinrichs, R. [Instituto de Geociências, UFRGS, P.O. Box 15001, 91501-970 Porto Alegre (Brazil); Vasconcellos, M.A.Z. [Instituto de Física, UFRGS, P.O. Box 15051, 91501-970 Porto Alegre (Brazil); Zoz, H.; Yigit, D.; Sun, X. [Zoz Group, 57482 Wenden (Germany)

    2013-12-15

    Different, partly complementary and partly redundant characterization methods were applied to study the transition of magnetite, graphite and MoS{sub 2} powders to mechanically alloyed nanostructures. The applied methods were: Transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), Raman spectroscopy (RS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The main objective was to prepare a model material providing the essential features of a typical tribofilm forming during automotive braking, and to assess the impact of different constituents on sliding behaviour and friction level. Irrespective of the initial grain size, the raw materials were transferred to a nanocrystalline structure and mixed on a nanoscopic scale during high energy ball milling. Whereas magnetite remained almost unchanged, graphite and molybdenum disulphide were transformed to a nanocrystalline and highly disordered structure. The observed increase of the coefficient of friction was attributed to a loss of lubricity of the latter ingredient due to this transformation and subsequent oxidation. - Highlights: • Characterization of microstructural changes induced by high energy ball milling • Assessment of the potential of different characterization methods • Impact of mechanical alloying on tribological performance revealed by tests • Preparation of an artificial third body resembling the one formed during braking.

  20. Fabrication of a Micro-Lens Array Mold by Micro Ball End-Milling and Its Hot Embossing

    Directory of Open Access Journals (Sweden)

    Peng Gao

    2018-02-01

    Full Text Available Hot embossing is an efficient technique for manufacturing high-quality micro-lens arrays. The machining quality is significant for hot embossing the micro-lens array mold. This study investigates the effects of micro ball end-milling on the machining quality of AISI H13 tool steel used in the micro-lens array mold. The micro ball end-milling experiments were performed under different machining strategies, and the surface roughness and scallop height of the machined micro-lens array mold are measured. The experimental results showed that a three-dimensional (3D offset spiral strategy could achieve a higher machining quality in comparison with other strategies assessed in this study. Moreover, the 3D offset spiral strategy is more appropriate for machining the micro-lens array mold. With an increase of the cutting speed and feed rate, the surface roughness of the micro-lens array mold slightly increases, while a small step-over can greatly reduce the surface roughness. In addition, a hot embossing experiment was undertaken, and the obtained results indicated higher-quality production of the micro-lens array mold by the 3D offset spiral strategy.

  1. Effect of Stiffness of Rolling Joints on the Dynamic Characteristic of Ball Screw Feed Systems in a Milling Machine

    Directory of Open Access Journals (Sweden)

    Dazhong Wang

    2015-01-01

    Full Text Available Dynamic characteristic of ball screw feed system in a milling machine is studied numerically in this work. In order to avoid the difficulty in determining the stiffness of rolling joints theoretically, a dynamic modeling method for analyzing the feed system is discussed, and a stiffness calculation method of the rolling joints is proposed based on the Hertz contact theory. Taking a 3-axis computer numerical control (CNC milling machine set ermined as a research object, the stiffness of its fixed joint between the column and the body together with the stiffness parameters of the rolling joints is evaluated according to the Takashi Yoshimura method. Then, a finite element (FE model is established for the machine tool. The correctness of the FE model and the stiffness calculation method of the rolling joints are validated by theoretical and experimental modal analysis results of the machine tool’s workbench. Under the two modeling methods of joints incorporating the stiffness parameters and rigid connection, a theoretical modal analysis is conducted for the CNC milling machine. The natural frequencies and modal shapes reveal that the joints’ dynamic characteristic has an important influence on the dynamic performance of a whole machine tool, especially for the case with natural frequency and higher modes.

  2. Microstructural changes and effect of variation of lattice strain on positron annihilation lifetime parameters of zinc ferrite nanocomposites prepared by high enegy ball-milling

    Directory of Open Access Journals (Sweden)

    Abhijit Banerjee

    2012-12-01

    Full Text Available Zn-ferrite nanoparticles were synthesized at room temperature by mechanical alloying the stoichiometric (1:1 mol% mixture of ZnO and α-Fe2O3 powder under open air. Formation of both normal and inverse spinel ferrite phases was noticed after 30 minutes and 2.5 hours ball milling respectively and the content of inverse spinel phase increased with increasing milling time. The phase transformation kinetics towards formation of ferrite phases and microstructure characterization of ball milled ZnFe2O4 phases was primarily investigated by X-ray powder diffraction pattern analysis. The relative phase abundances of different phases, crystallite size, r.m.s. strain, lattice parameter change etc. were estimated from the Rietveld powder structure refinement analysis of XRD data. Positron annihilation lifetime spectra of all ball milled samples were deconvoluted with three lifetime parameters and their variation with milling time duration was explained with microstructural changes and formation of different phases with increase of milling time duration.

  3. XRD and HREM studies from the decomposition of icosahedral AlCuFe single-phase by high-energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Patino-Carachure, C.; Tellez-Vazquez, O. [Instituto de Investigaciones Metalurgicas, UMSNH, Edificio U, Ciudad Universitaria, Morelia, Michoacan 58000 (Mexico); Rosas, G., E-mail: grtrejo@umich.mx [Instituto de Investigaciones Metalurgicas, UMSNH, Edificio U, Ciudad Universitaria, Morelia, Michoacan 58000 (Mexico)

    2011-10-13

    Highlights: > Point defects induced during milling leading to an order-disorder quasicrystal transition. > Nanoquasicrystalline regions of 12 nm are obtained. > Highly ordered i-phase with high symmetry transforms to a crystalline phase of intermetallic character and lower symmetry. - Abstract: In this investigation the Al{sub 64}Cu{sub 24}Fe{sub 12} alloy was melted in an induction furnace and solidified under normal casting conditions. In order to obtain the icosahedral phase (i-phase) in a single-phase region, the as-cast sample was subject to a heat treatment at 700 deg. C under argon atmosphere. Subsequently, the i-phase was milled for different times in order to evaluate phase stability under heavy deformation. X-ray diffraction (XRD) and high-resolution electron microscopy (HREM) analysis were conducted to the structural characterization of ball-milled powders. XRD results indicated a reduction in quasicrystal size during mechanical ball milling to about 30 h. HREM analysis revealed the presence of aperiodic nano-domains, for example, with apparent fivefold symmetry axis. Therefore, the i-phase remains stable over the first 30 h of ball-milling time. However, among 30-50 h of mechanical milling the i-phase transforms progressively into {beta}-cubic phase.

  4. Sensor Placement Optimization of Vibration Test on Medium-Speed Mill

    Directory of Open Access Journals (Sweden)

    Lihua Zhu

    2015-01-01

    Full Text Available Condition assessment and decision making are important tasks of vibration test on dynamic machines, and the accuracy of dynamic response can be achieved by the sensors placed on the structure reasonably. The common methods and evaluation criteria of optimal sensor placement (OSP were summarized. In order to test the vibration characteristic of medium-speed mill in the thermal power plants, the optimal placement of 12 candidate measuring points in X, Y, and Z directions on the mill was discussed for different targeted modal shapes, respectively. The OSP of medium-speed mill was conducted using the effective independence method (EfI and QR decomposition algorithm. The results showed that the order of modal shapes had an important influence on the optimization results. The difference of these two methods on the sensor placement optimization became smaller with the decrease of the number of target modes. The final scheme of OSP was determined based on the optimal results and the actual test requirements. The field test results were basically consistent with the finite element analysis results, which indicated the sensor placement optimization for vibration test on the medium-speed mill was feasible.

  5. OPTIMIZATION OF CARBIDE BALL NOSE END MILL PROFILE ANGLES IN MACHINING INCONEL 718

    OpenAIRE

    Ghasem Esmati, Behrooz Arezoo*

    2017-01-01

    Cutting tools nearly make up 30% of all the manufacturing cost. Modeling and simulation of machining is essential for improving and increasing efficiency of the process. Inconel 718 alloy which is an iron-nickel based superalloy is widely used in rocket engines, turbine blades, molds and extrusion containers. The flute profile is the main part in the milling cutting tool body and has an important effect on the tool life and machining quality in milling processes. The flute profile includes ra...

  6. Minimization of Surface Roughness and Tool Vibration in CNC Milling Operation

    Directory of Open Access Journals (Sweden)

    Sukhdev S. Bhogal

    2015-01-01

    Full Text Available Tool vibration and surface roughness are two important parameters which affect the quality of the component and tool life which indirectly affect the component cost. In this paper, the effect of cutting parameters on tool vibration, and surface roughness has been investigated during end milling of EN-31 tool steel. Response surface methodology (RSM has been used to develop mathematical model for predicting surface finish, tool vibration and tool wear with different combinations of cutting parameters. The experimental results show that feed rate is the most dominating parameter affecting surface finish, whereas cutting speed is the major factor effecting tool vibration. The results of mathematical model are in agreement with experimental investigations done to validate the mathematical model.

  7. Effect of combination ultrasonic and ball milling techniques of commercial fillers dispersion on mechanical properties of natural rubber (NR) latex films

    Science.gov (United States)

    Hamran, Noramirah; Rashid, Azura A.

    2017-07-01

    Commercial fillers such as silica and carbon black generally impart the reinforcing effects in dry rubber compound, but have an adverse effect on Natural rubber (NR) latex compounds. The addition of commercial fillers in NR latex has reduced the mechanical properties of NR latex films due to the destabilization effect in the NR latex compounds which govern by the dispersion quality, particle size and also the pH of the dispersion itself. The ball milling process is the conventional meth od of preparation of dispersions and ultrasonic has successfully used in preparation of nano fillers such as carbon nanotube (CNT). In this study the combination between the conventional methods; ball milling together the ultrasonic method were used to prepare the silica and carbon black dispersions. The different duration of ball milling (24, 48 and 72 hours) was compared with the ultrasonic method (30, 60, 90 and 120 minutes). The combination of ball milling and ultrasonic from the optimum individual technique was used to investigate the reduction of particle size of the fillers. The particle size analyzer, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) test were carried out to investigate the obtained particle size and the tensile and tear test were carried out to investigate the mechanical properties of the NR latex films. The reduction of filler particle size is expected to impart the properties of NR latex films.

  8. Multitudinous industrialized fabrication of BNNT with high-energy ball milling and arc-discharge-aided template methods

    Science.gov (United States)

    Wang, Shouren; Wen, Daosheng; Wang, Gaoqi; Yang, Liying; Guo, Peiquan; Qiao, Yang

    2017-10-01

    A novel large-scale fabrication technology for single-walled boron nitride nanotube (BNNT) relying on a template of single-walled carbon nanotube (SWCNTs) was introduced. In order to obtain large-scale product, the high-energy ball milling-aided heating technology was used to promote the formation of BNNTs. And arc-discharge methods were used to provide nitrogen ion source. The products were oxidized at 800 °C in air atmosphere to obtain pure BNNTs. The structure and morphology of BNNTs were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermogravimetric analysis. The multitudinous industrialized preparation methods for BNNTs were realized as a simple and effective route.

  9. Influence of Process Control Agent on Characterization and Structure of Micron Chitosan Powders Prepared by Ball Milling Method

    Directory of Open Access Journals (Sweden)

    ZHANG Chuan-jie

    2016-12-01

    Full Text Available With ethyl alcohol or distilled water as process control agent (PCA, micron chitosan powder was prepared by ball milling method. The yield rate, particle size distribution, micro morphology, viscosity average molecular mass, chemical and crystal structures, and thermal properties of these different micron chitosan powders were measured. The results indicate that the yield rate of micron chitosan powders prepared with ethyl alcohol as PCA increases significantly, and improves to 94.7% from 25% while the amount of ethyl alcohol is 0.75mL/g. The particle size distribution of micron chitosan powder prepared with ethyl alcohol as PCA is concentrated, while the D50 and D90 in size are 824nm and 1629nm respectively. Chitosan do not react with ethyl alcohol used as PCA, but the viscosity average molecular mass of prepared micron chitosan powder decreases by 23%, the crystal structures are destroyed slightly, and its thermal stability is slightly weakened.

  10. Optical and dielectric study of strontium modified barium zirconium titanate ceramic prepared by high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Badapanda, T., E-mail: badapanda.tanmaya@gmail.com [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar, Odisha 752054 (India); Sarangi, S.; Behera, B. [School of Physics, Sambalpur University, Jyoti Vihar, Sambalpur, Odisha 768019 (India); Parida, S. [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar, Odisha 752054 (India); Saha, S.; Sinha, T.P. [Department of Physics, Bose Institute, Kolkata 700009 (India); Ranjan, Rajeev [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Sahoo, P.K. [School of Physical Science, National Institute of Science Education and Research (NISER), Bhubaneswar, Odisha (India)

    2015-10-05

    Highlights: • Submicron size strontium doped BZT ceramics were prepared by high energy ball milling. • Structural analysis was done by Reitveld refinement and Raman analysis. • Decrement in transition temperature and increment in diffusivity is observed with doping. • Remnant polarization decreases and coercive filed increases with doping. • Optical study was done by UV–vis spectroscopy and the optical band gap increases with doping. - Abstract: Strontium modified barium zirconium titanate with general formula Ba{sub 1−x}Sr{sub x}Zr{sub 0.05}Ti{sub 0.95}O{sub 3} ceramics have been prepared by solid state and high energy ball milling technique. The X-ray diffraction and Rietveld refinement studies show that all the compositions have single phase symmetry. The composition BaZr{sub 0.05}Ti{sub 0.95}O{sub 3} shows orthorhombic symmetric with space group Amm2. The structure changes from orthorhombic to tetragonal with strontium doping up to x = 0.3 and with further addition, changes to cubic. The scanning electron micrographs show that the grain size decreases with increase in strontium content. The temperature dependent dielectric behavior shows three phase transition in the parent material which merges with an increase in Sr content. The transition temperature and dielectric constant decreases with an increase in Sr concentration. The phase transition becomes more diffused with increment in doping concentration. The ferroelectric behavior of the ceramics is studied by the hysteresis loop. The optical behavior is studied by the UV–visible spectroscopy and found that the optical band gap increases with Sr concentration.

  11. Use of high energy ball milling to study the role of graphene nanoplatelets and carbon nanotubes reinforced magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, Muhammad, E-mail: rashadphy87@gmail.com [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Pan, Fusheng, E-mail: fspan@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing, Chongqing 401123 (China); Zhang, Jianyue [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Asif, Muhammad [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-10-15

    Graphene nanoplatelets (few layer graphene) and carbon nanotubes were used as reinforcement fillers to enhance the mechanical properties of AZ31 magnesium alloy through high energy ball milling, sintering, and hot extrusion techniques. Experimental results revealed that tensile fracture strain of AZ31 magnesium alloy was enhanced by +49.6% with 0.3 wt.% graphene nanoplatelets compared to −8.3% regression for 0.3 wt.% carbon nanotubes. The tensile strength of AZ31 magnesium alloy was decreased (−11.2%) with graphene nanoplatelets addition, while increased (+7.7%) with carbon nanotubes addition. Unlike tensile test, compression tests showed different trend. The compression strength of carbon nanotubes-AZ31 composite was +51.2% greater than AZ31 magnesium alloy as compared to +0.6% increase for graphene nanoplatelets. The compressive fracture strain of carbon nanotubes-AZ31 composite was decreased (−14.1%) while no significant change in fracture strain of graphene nanoplatelets-AZ31 composite was observed. The X-ray diffraction results revealed that addition of reinforcement particles weaken the basal textures which affect the composite's yield asymmetry. Microstructure evaluation revealed the absence of intermetallic phase formation between reinforcements and matrix. The carbon reinforcements in AZ31 magnesium alloy dissolve and isolate β phases throughout the matrix. The increased fracture strain and mechanical strength of graphene nanoplatelets and carbon nanotubes-AZ31 composites are attributed to large specific surface area of graphene nanoplatelets and stiffer nature of carbon nanotubes respectively. - Highlights: • Powder metallurgy method was used to fabricate magnesium composites. • The AZ31-carbon materials composite were blended using ball milling. • The reinforcement particles weaken the basal texture which affects yield asymmetry of composites. • AZ31-graphene nanoplatelets composite exhibited impressive increase in tensile elongation

  12. Effect of ball milling on properties of porous Ti–7.5Mo alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung, Taiwan, ROC (China); Institute of Biomedical Engineering and Materials Science, Central Taiwan University of Science and Technology, Taichung, Taiwan, ROC (China); Chang, Tien-Yu [Department of Mechanical and Automation Engineering, Da-Yeh University, Changhua, Taiwan, ROC (China); Ho, Wen-Fu, E-mail: fujii@mail.dyu.edu.tw [Advanced Materials and BioMaterials Lab, Department of Materials Science and Engineering, Da-Yeh University, Changhua, Taiwan, ROC (China)

    2014-01-05

    Highlights: • Porous Ti–7.5Mo was successfully prepared through a space-holder sintering method. • The mechanical properties of porous Ti–7.5Mo are comparable to those of natural bone. • Porous Ti–7.5Mo exhibited better apatite-forming abilities after surface treatment. • The inner surfaces of porous specimens exhibited better apatite-inducing ability. -- Abstract: Porous titanium has been used to anchor implants through bone growth into the porous structure. This bone ingrowth provides a strong implant/bone bond, and the pores may be interconnected three-dimensionally to provide enough space for the attachment and proliferation of new bone tissues and to facilitate the transport of body fluids. In the present study, porous scaffolds fabricated from three kinds of ball-milled Ti–7.5Mo alloy particles were successfully prepared through a space-holder sintering method, and the compressive strengths and moduli of all the sintered porous Ti–7.5Mo conform to the basic mechanical property requirement of cancellous bones. However, the porous Ti–7.5Mo fabricated from particles ball milled for 15 h (TM15) possesses a relatively higher strength. Moreover, the elastic modulus of TM15 is 1.72 GPa, which is comparable to that reported for cancellous bone. Furthermore, the porous TM15 alloy exhibited better apatite-forming abilities after pretreatment (with NaOH or NaOH + water) and subsequent immersion in simulated body fluid (SBF) at 37 °C. After soaking in a SBF solution for 21 days, a dense apatite layer covered the inner and outer surfaces of the pretreated porous TM15 substrates, thereby providing favorable bioactive conditions for bone bonding and growth.

  13. Removal of fluoride from drinking water using modified ultrafine tea powder processed using a ball-mill

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Huimei; Xu, Lingyun; Chen, Guijie; Peng, Chuanyi [School of Tea & Food Science and Technology, Anhui Agricultural University/State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, Anhui (China); Ke, Fei [School of Tea & Food Science and Technology, Anhui Agricultural University/State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, Anhui (China); School of Science, Anhui Agricultural University, Hefei 230036 (China); Liu, Zhengquan; Li, Daxiang; Zhang, Zhengzhu [School of Tea & Food Science and Technology, Anhui Agricultural University/State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, Anhui (China); Wan, Xiaochun, E-mail: xcwan@ahau.edu.cn [School of Tea & Food Science and Technology, Anhui Agricultural University/State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, Anhui (China)

    2016-07-01

    Highlights: • Ultrafine tea powder (UTP) was prepared by ball-milling. • A novel and high efficient biosorbent from ultrafine tea powder (UTP) for the removal of fluoride from drinking water was prepared. • Loaded ultrafine tea powder adsorbed more fluoride adsorption than loaded tea waste. • UTP-Zr performed well over a considerably wide pH range, from 3.0 to 10.0. • UTP-Zr retains Zr metal ion during defluoridation, limiting secondary pollution. - Abstract: A low-cost and highly efficient biosorbent was prepared by loading zirconium(IV) onto ball-milled, ultrafine tea powder (UTP-Zr) for removal of fluoride from drinking water. To evaluate the fluoride adsorption capacity of UTP-Zr over a wide range of conditions, the biosorbent dosage, contact time, initial pH, initial fluoride concentration and presence of other ions were varied. UTP-Zr performed well over the considerably wide pH range of 3–10. The residual concentration of Zr in the treated water was below the limit of detection (0.01 mg/L). Fluoride adsorption by the UTP-Zr biosorbent followed the Langmuir model, with a maximum adsorption capacity of 12.43 mgF/g at room temperature. The fluoride adsorption kinetics fit the pseudo-second-order kinetic model. The synthesized biosorbent was characterized by BET, SEM, EDS, XRD and XPS to reveal how UTP-Zr interacts with fluoride. Results from this study demonstrated that UTP-based biosorbents will be useful and safe for the removal of fluoride from drinking water.

  14. Physicochemical properties of direct compression tablets with spray dried and ball milled solid dispersions of tadalafil in PVP-VA.

    Science.gov (United States)

    Wlodarski, K; Tajber, L; Sawicki, W

    2016-12-01

    The aim of this research was to develop immediate release tablets comprising solid dispersion (IRSDTs) of tadalafil (Td) in a vinylpyrrolidone and vinyl acetate block copolymer (PVP-VA), characterized by improved dissolution profiles. The solid dispersion of Td in PVP-VA (Td/PVP-VA) in a weight ratio of 1:1 (w/w) was prepared using two different processes i.e. spray drying and ball milling. While the former process has been well established in the formulation of IRSDTs the latter has not been exploited in these systems yet. Regardless of the preparation method, both Td/PVP-VA solid dispersions were amorphous as confirmed by PXRD, DSC and FTIR. However, different morphology of particles (SEM) resulted in differences in water apparent solubility and disk intrinsic dissolution rate (DIDR). Both solid dispersions and crystalline Td were successfully made into directly compressible tablets at three doses of Td, i.e. 2.5mg, 10mgand20mg, yielding nine different formulations (D1-D9). Each of the lots met the requirements set by Ph.Eur. and was evaluated with respect to appearance, diameter, thickness, mass, hardness, friability, disintegration time and content of Td. IRSDTs performed as supersaturable formulations and had significantly improved water dissolution profiles in comparison with equivalent tablets containing crystalline Td and the marketed formulations. Tablets with both spray dried and ball milled Td/PVP-VA revealed the greatest improvement in dissolution depending on the investigated doses, i.e. 2.5mgand20mg, respectively. Also, dissolution of Td from Td/PVP-VA delivered in different forms occurred in the following order: powders>tablets>capsules. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Artificial Neural Network Modelling of Vibration in the Milling of AZ91D Alloy

    Directory of Open Access Journals (Sweden)

    Ireneusz Zagórski

    2017-09-01

    Full Text Available The paper reports the results of artificial neural network modelling of vibration in. a milling process of magnesium alloy AZ91D by a TiAlN-coated carbide tool. Vibrations in machining processes are regarded as an additional, absolute machinability index. The modelling was performed using the so-called “black box” model. The best fit was determined for the input and output data obtained from the machining process. The simulations were performed by the Statistica software using two types of neural networks: RBF (Radial Basis Function and MLP (Multi-Layered Perceptron.

  16. Surface Generation Modeling in Ball Nose End Milling: a review of relevant literature

    DEFF Research Database (Denmark)

    Bissacco, Giuliano

    One of the most common metal removal operation used in industry is the milling process. This machining process is well known since the beginning of last century and has experienced, along the years, many improvements of the basic technology, as concerns tools, machine tools, coolants/lubricants, ...

  17. Interfacial Reaction During High Energy Ball Milling Dispersion of Carbon Nanotubes into Ti6Al4V

    Science.gov (United States)

    Adegbenjo, A. O.; Olubambi, P. A.; Potgieter, J. H.; Nsiah-Baafi, E.; Shongwe, M. B.

    2017-10-01

    The unique thermal and mechanical properties of carbon nanotubes (CNTs) have made them choice reinforcements for metal matrix composites (MMCs). However, there still remains a critical challenge in achieving homogeneous dispersion of CNTs in metallic matrices. Although high energy ball milling (HEBM) has been reported as an effective method of dispersing CNTs into metal matrices, a careful selection of the milling parameters is important not to compromise the structural integrity of CNTs which may cause interfacial reactions with the matrix. In this study, multi-walled carbon nanotubes (MWCNTs) were purified by annealing in argon and vacuum atmospheres at 1000 and 1800 °C, respectively, for 5 h to remove possible metallic catalyst impurities. Subsequently, 1, 2 and 3 wt.% MWCNTs were dispersed by adapted HEBM into Ti6Al4V alloy metal matrix. Raman spectroscopy (RS), x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectrometry and transmission electron microscopy techniques were used to characterize the as-received and annealed MWCNTs, as well as the admixed MWCNT/Ti6Al4V nanocomposite powders. The experimental results showed that vacuum annealing successfully eliminated retained nickel (Ni) catalysts from MWCNTs, while the adapted HEBM method achieved a relative homogeneous dispersion of MWCNTs into the Ti6Al4V matrix and helped to control interfacial reactions between defective MWCNTs and the metal matrix.

  18. Combining hot-compressed water and ball milling pretreatments to improve the efficiency of the enzymatic hydrolysis of eucalyptus

    Directory of Open Access Journals (Sweden)

    Sakaki Tsuyoshi

    2008-04-01

    Full Text Available Abstract Background Lignocellulosic biomass such as wood is an attractive material for fuel ethanol production. Pretreatment technologies that increase the digestibility of cellulose and hemicellulose in the lignocellulosic biomass have a major influence on the cost of the subsequent enzymatic hydrolysis and ethanol fermentation processes. Pretreatments without chemicals such as acids, bases or organic solvents are less effective for an enzymatic hydrolysis process than those with chemicals, but they have a less negative effect on the environment. Results The enzymatic digestibility of eucalyptus was examined following a combined pretreatment without chemicals comprising a ball milling (BM and hot-compressed water (HCW treatment. The BM treatment simultaneously improved the digestibility of both glucan and xylan, and was effective in lowering the enzyme loading compared with the HCW treatment. The combination of HCW and BM treatment reduced the BM time. The eucalyptus treated with HCW (160°C, 30 minutes followed by BM (20 minutes had an approximately 70% yield of total sugar with a cellulase loading of 4 FPU/g substrate. This yield was comparable to the yields from samples treated with HCW (200°C, 30 minutes or BM (40 minutes hydrolyzed with 40 FPU/g substrate. Conclusion The HCW treatment is useful in improving the milling efficiency. The combined HCW-BM treatment can save energy and enzyme loading.

  19. Influence of composition, grain size, and oxide particles on the strength of consolidated ball-milled iron

    Science.gov (United States)

    Benito, J. A.; Gregoire, V.; Casas, C.; Cabrera, J. M.

    2014-08-01

    In this paper iron powders with two oxygen content (0.2 and 0.6% wt.) have been mechanically milled and consolidated by hot static pressing at different temperatures to obtain different grain sizes. At lower temperatures the grain size was in the nanostructured and ultrafine range and with increasing temperature abnormal grain growth was observed for both compositions. This led to the development of bimodal grain size distributions. In the samples with lower oxygen content the grain size and the percentage of coarse grain areas were larger than in the case of high oxygen content. The strength and ductility have been determined by tensile tests. For low oxygen content, the presence of large coarse grains allowed plastic strain in some cases, and for the samples consolidated at higher temperatures, yield strength of 865 MPa with a 8% total strain were obtained. For the samples with high oxygen content plastic deformation was no possible in any case. The observed stress for both compositions was analysed by two approaches, one based exclusively in grain boundary strengthening and the other one based in two effects acting at the same time: grain boundary and particle strengthening. Whereas grain boundary strengthening seems to fit with the strength of the samples in the nanostructured range, when coarse ferrite grains appear the addition of particle strengthening help to get better results. This indicates that the presence of oxides dissolved inside the large grains reinforce the structure of ball-milled iron.

  20. Interfacial Reaction During High Energy Ball Milling Dispersion of Carbon Nanotubes into Ti6Al4V

    Science.gov (United States)

    Adegbenjo, A. O.; Olubambi, P. A.; Potgieter, J. H.; Nsiah-Baafi, E.; Shongwe, M. B.

    2017-12-01

    The unique thermal and mechanical properties of carbon nanotubes (CNTs) have made them choice reinforcements for metal matrix composites (MMCs). However, there still remains a critical challenge in achieving homogeneous dispersion of CNTs in metallic matrices. Although high energy ball milling (HEBM) has been reported as an effective method of dispersing CNTs into metal matrices, a careful selection of the milling parameters is important not to compromise the structural integrity of CNTs which may cause interfacial reactions with the matrix. In this study, multi-walled carbon nanotubes (MWCNTs) were purified by annealing in argon and vacuum atmospheres at 1000 and 1800 °C, respectively, for 5 h to remove possible metallic catalyst impurities. Subsequently, 1, 2 and 3 wt.% MWCNTs were dispersed by adapted HEBM into Ti6Al4V alloy metal matrix. Raman spectroscopy (RS), x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectrometry and transmission electron microscopy techniques were used to characterize the as-received and annealed MWCNTs, as well as the admixed MWCNT/Ti6Al4V nanocomposite powders. The experimental results showed that vacuum annealing successfully eliminated retained nickel (Ni) catalysts from MWCNTs, while the adapted HEBM method achieved a relative homogeneous dispersion of MWCNTs into the Ti6Al4V matrix and helped to control interfacial reactions between defective MWCNTs and the metal matrix.

  1. Synthesis of AlN-TiN nanostructured composite powder by reactive ball milling and subsequent thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Mashhadi, H. Amini, E-mail: hossein1@shock.smrc.kumamoto-u.ac.j [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan); Manikandan, P.; Suetsugu, R. [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan); Tanaka, S. [Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan); Hokamoto, K. [Shock Wave and Condensed Matter Research Center, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan)

    2010-09-17

    Research highlights: {yields} A part of AlN was found to be gradually reduced by Ti during MA and Ti(Al,N) solid solution formed after early stages of milling. {yields} The particle size of supersaturated Ti(Al,N) solid solution and AlN reduced to submicron size and nanocrystalline structure as evident from XRD and SEM results. {yields} The lattice parameter and interplanar distance of Ti shows that all of the decomposed Al dissolved in the Ti lattice by MA and causes its contraction, while only 1 at.% of N dissolves to form Ti(Al,N) solid solution and leads to its dilation and the remaining N reacts with Ti to form TiN. {yields} Annealing of 360 ks MA powder leads to phase transformation as a result of increased thermal diffusivity, the formation of more TiN phase with more under-stoichiometric characteristic, as well as stress releasing and grain growth. - Abstract: In the present article, synthesis of AlN-TiN nanostructured composite by high-energy ball milling process (HEM) of Ti and AlN by 1:1 molar ratio and subsequent heat treatment was investigated. The microstructural evolution of samples was studied by scan electron microscopy (SEM) and energy dispersive X-ray analysis (EDS), composition map analysis by electron probe micro-analyzer (EPMA) and phase determination using X-ray diffraction (XRD) patterns. It was found that a Ti(Al,N) solid solution was formed at the early stages of milling and while Al causes the Ti lattice to contract, N has the opposite effect. The nonlinear variation of interplanar distance and c/a ratio of Ti is considered due to the competition between these two processes during MA and finally led to complete dissolution of Al and only 1 at.% of N in Ti lattice. On further milling, mechanochemical reaction between Ti solid solution and AlN took place in the gradual mode which led to the formation of TiN with an average crystallite size of 10 nm. It is generally acknowledged that the reactions between Ti and AlN includes three stages: (i

  2. Grinding of Class-F fly ash using planetary ball mill: A simulation study to determine the breakage kinetics by direct- and back-calculation method

    Directory of Open Access Journals (Sweden)

    Dilip K. Rajak

    2017-12-01

    Full Text Available Dry grinding of Class F fly ash (FA was carried out using the planetary ball mill to obtain mechanically activated nanostructured FA particles. The resulting FA powders were characterized for (i particle size: dynamic light scattering and sieve analyzer, (ii specific surface area: BET-analyzer, (iii structure: X-ray diffractometer, (iv chemical composition: field emission scanning electron microscope with the electron diffraction spectrum analyzer and x-ray fluorescence analyzer, and (v aggregation and shape of the particles: Fourier-transformed infra-red spectrometer and scanning electron microscope. A significant enhancement in surface and bulk properties of milled FA was obtained over fresh FA. The breakage parameters (i.e., the specific rate of breakage and primary breakage distribution function of FA were determined by the direct experimental method using the narrowly-sized fraction of FA over the short grinding period under identical milling environment. A relatively simple back-calculation method was employed to determine above breakage parameters of FA also using time-variant milling data that were obtained after the grinding of distributed-sized FA feed. The parameters obtained from the direct experimental and back-calculation method yielded comparative milling simulation results with the acceptable accuracy. Keywords: Planetary ball mill, Fly ash, Population balance model, Direct- and back-calculation method, Breakage parameters, Parameter optimization

  3. Characterization and x-ray absorption spectroscopy of ilmenite nanoparticles derived from natural ilmenite ore via acid-assisted mechanical ball-milling process

    Science.gov (United States)

    Phoohinkong, Weerachon; Pavasupree, Sorapong; Wannagon, Anucha; Sanguanpak, Samunya; Boonyarattanakalin, Kanokthip; Mekprasart, Wanichaya; Pecharapa, Wisanu

    2017-09-01

    In this work activated ilmenite nanoparticles were prepared by chemical-assisted in mechanical ball-milling process from ilmenite ore as starting raw material. The effect of milling process on their phase composition, particle size, surface morphology and local structure were investigated. Phase identification and crystalline structure of ilmenite mineral, milled samples and subsequent leached residues were characterized by x-ray diffraction (XRD). Meanwhile, the distorted octahedral structure and the oxidation state of relevant elements in ilmenite ore and activated ilmenite obtained by different process conditions were analyzed by x-ray absorption spectroscopy (XAS). Particle size and morphologies of the samples were monitored by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Three dominant peaks of TiO2 rutile, FeTiO3, and Fe2TiO4 are obviously adulterated in XRD patterns after mechanical milling with water and acid solution when comparing to precursor mineral. However, the contaminated phase of FeTiO3 and Fe2TiO4 was readily decreased by acid-assisted mechanical ball-milling. The enhancement in leaching process of ilmenite residue after milling can be obtained with sulfuric acid. This result suggests that iron contaminated phase could be leached from the sample resulting to the decrease in Fe environment around Ti atom. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

  4. Structural; magnetic and catalytic properties of nanocrystalline Cu0.5Zn0.5Fe2O4 synthesized by microwave combustion and ball milling methods

    Science.gov (United States)

    Mahmoud, M. H.; Hassan, Azza M.; Said, Abd El-Aziz A.; Hamdeh, H. H.

    2016-06-01

    Effects of high energy ball-milling on nanosized Cu0.5Zn0.5Fe2O4 powders were studied at 30 and 330 min of milling. The powders were initially synthesized from its stoichiometric metal nitrates and urea mixtures, using a microwave assisted combustion method. Ball-milling induced electromechanical reaction was examined by XRD, TEM, Mössbauer spectroscopy, magnetization, and catalytic performance by exploring potential changes in size, phases and chemical structure. Before Milling, the as-prepared powders were comprised of small grains of poor spinel crystallinity and very small crystallite size, and a minor α-Fe2O3 phase. Progressive milling significantly reduced the grain size, increased chemical disorder, and reduced the hematite phase. These changes are also manifested in the magnetization measurements. The Catalytic activity performance was carried out using dehydrogenation of isopropyl alcohol. The observed activity was correlated to the presence of Cu2+ and Fe3+ catalysts at octahedral sites before and after milling.

  5. Properties of Y-TZP/Al{sub 2}O{sub 3} ceramic nanocomposites obtained by high-energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Santos, C. [Universidade de Sao Paulo - Escola de Engenharia de Lorena (USP-EEL), Polo Urbo-Industrial, Gleba AI-6, s/n, Lorena-SP, CEP 12600-000 (Brazil); Universidade do Estado do Rio de Janeiro, Faculdade de Tecnologia (UERJ-FAT), Rodovia Presidente Dutra, km 298, Resende-RJ, CEP 27511-971 (Brazil)], E-mail: claudinei@demar.eel.usp.br; Koizumi, M.H.; Daguano, J.K.M.F.; Santos, F.A. [Universidade de Sao Paulo - Escola de Engenharia de Lorena (USP-EEL), Polo Urbo-Industrial, Gleba AI-6, s/n, Lorena-SP, CEP 12600-000 (Brazil); Elias, C.N. [Instituto Militar de Engenharia - Departamento de Ciencia e Engenharia de Materiais (IME - DCEM), Pca. General Tiburcio, 80, Praia Vermelha, Rio de Janeiro-RJ, CEP 22290-270 (Brazil); Universidade do Estado do Rio de Janeiro, Faculdade de Tecnologia (UERJ-FAT), Rodovia Presidente Dutra, km 298, Resende-RJ, CEP 27511-971 (Brazil); Ramos, A.S. [Universidade do Vale do Paraiba - Instituto de Pesquisa e Desenvolvimento (UNIVAP-IP and D), Av. Shishima Hifumi, 2911, Urbanova, S.J.Campos-SP, CEP 12244-000 (Brazil)

    2009-02-25

    In this work, the synthesis of Y{sub 2}O{sub 3} stabilized tetragonal zirconia polycrystals (Y-TZP)-alumina (Al{sub 2}O{sub 3}) powder mixture was performed by high-energy ball milling and the sintering behavior of this composite was investigated. In order to understand the phase transformations occurring during ball milling, samples were collected after different milling times, from 1 to 60 h. The milled powders were compacted by cold uniaxial pressing and sintered at 1400 and 1600 deg. C. Both powders and sintered samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry analysis (EDS) and mechanical properties. Fully dense samples were obtained after sintering at 1600 deg. C, while the samples sintered at 1400 deg. C presented a full density for powder mixtures milled for 30 and 60 h. Fracture toughness and Vickers hardness values of the Y-TZP/Al{sub 2}O{sub 3} nanocomposite were improved due to dispersed Al{sub 2}O{sub 3} grains and reduced ZrO{sub 2} grain size. Samples sintered at 1400 deg. C, based on powders milled for 60 h, presented high K{sub IC} and hardness values near to 8.0 MPam{sup 1/2} and 15 GPa, respectively.

  6. Synthesis and Characterization of Aluminum-Nanodiamond Composite Powders by High Energy Ball Milling

    Science.gov (United States)

    2011-12-01

    grind samples from 0.1 to 5.0 grams. For MA, cryomilling is advantageous because the cryogenic milling temperature limits the effectiveness of...fineness approaches a limit. The primary factors leading to the grind limit are: Increasing resistance to fracture, agglomeration, excessive...clearance between impacting surfaces, surface roughness of the grinding media, increasing apparent viscosity as particle size decreases, and decreasing

  7. Computational and experimental analysis of machine tool vibrations in micro-milling

    Directory of Open Access Journals (Sweden)

    Sagris Dimitrios

    2017-01-01

    Full Text Available In machining processes, it is necessary to study the vibration phenomena which take place in cutting zone between the cutting tool and the workpiece in order to ascertain the factors that affect them. The subject of this paper is to identify the influence of the cutting parameters and the dynamic characteristics of the machine tool spindle and the cutting tool on the vibrations by means of FEM analysis. A FEM modal analysis of the machine tool spindle in combination with cutting force measurements are used to build up a transient FEM model in time domain in order to study the vibrations induced by the cutting process. The results of the transient FEM model will serve for further analysis to find out the optimum cutting parameters in micro-milling.

  8. The optimization of predicting the liquefy of pulp in a ball mill at variable flow of water in sand of the classifier

    Directory of Open Access Journals (Sweden)

    Кondratets V.О.

    2017-04-01

    Full Text Available To diminish the cost of iron-ore concentrate is possible by stabilization in the ball mill ratio ore / water, and this work is devoted to find it. In this work we used an algorithmic approach of the determination of the controlled value, the dynamic programming method and the Gauss-Seidel’s method, method of analytical calculations with using the mathematical model of the process, the theory of accuracy, the theory of signal filtering, the theory of sensitivity of optimum, modeling of the processes in the sand trough of the single-spiral classifier during valuing the water supply regimes in the sands. Prediction of ore / water ratio at a constant flow of the water in the sand of the classifier optimization of the selection information means by accuracy is made at the level of permissible error of ± 3,0 % with a significant reserve (of error in a conditions of high error of measurement of pulp, it improves the indices of the ball mill, but has identified detects. Much better results provides regimen of stabilization pulp liquefaction in the sand trough. Prediction the index in these conditions could provide at level of error ± 3,0 % in case of increasing the accuracy of the conveyor balance. The work demonstrates for the first time the possibility of creating devices of ratio ore / water prediction in a ball mill in the stabilization of pulp liquefaction in the sand trough by implementation of the algorithmic approach and optimize the choice of measuring devices by accuracy. The practical significance consists in the increasing of production of the ball mill and economy electricity, steel balls and inwall.

  9. Experimental and theoretical study of phase transitions under ball milling; Etude experimentale et modelisation des changements de phases sous broyage a haute energie

    Energy Technology Data Exchange (ETDEWEB)

    Pochet, P

    1997-12-31

    The aim of this work was to determine how phase transition s under ball-milling depend on the milling conditions and to find out if one can rationalize such transitions with the theory of driven alloys. We have chosen two phase transitions: the order-disorder transition in Fe Al and the precipitation-dissolution NiGe. In the case of Fe Al we have found that the steady-state long range order parameter achieved under ball milling intensity; moreover the same degree of order is achieved starting from an ordered alloy or a disordered solid solution. On the way to fully disordered state the degree of order either decreases monotonically or goes through a short lived transient state. This behaviour is reminiscent of a first order transition while the equilibrium transition is second order. All the above features are well reproduced by a simple model of driven alloys, which was originally build for alloys under irradiation. The stationary degree of order results of two competitive atomic jump mechanisms: the forced displacements induced by the shearing of the grains, and the thermally activated jumps caused by vacancies migrations. Finally we have performed atomistic simulations with a Monte Carlo kinetic algorithm, which revealed the role of the fluctuations in the intensity of the forcing. Moreover we have shown that specific atomistic mechanisms are active in a dilute NiGe solid solution which might lead to ball milling induced precipitation in under-saturated solid solution. (author). 149 refs.

  10. Effect of Ni addition on the preparation of Al2O3–TiB2 composites using high-energy ball milling

    Directory of Open Access Journals (Sweden)

    Wei Yang

    2014-12-01

    Full Text Available Al2O3–TiB2 composites were synthesized using high-energy ball milling from starting powders containing Al, TiO2, and B2O3. To explore the effect of the addition of another ductile metallic phase during milling, 15 wt.% Ni was added to a sample of the starting powders. The phase transformations and microstructure of the milled powder mixtures were investigated using X-ray diffraction and electron microscopy. The results showed that the Ni addition facilitated the mechanochemical reaction between the Al, TiO2, and B2O3. Before the appearance of the Al2O3–TiB2 composite, the intermediate product NiAl was formed by a gradual exothermic reaction. With continued milling, the final phases of Al2O3–TiB2 and Ni were obtained.

  11. Analytical Modeling of a Ball Screw Feed Drive for Vibration Prediction of Feeding Carriage of a Spindle

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2016-01-01

    Full Text Available An analytical modeling approach for ball screw feed drives is proposed to predict the dynamic behavior of the feeding carriage of a spindle. Mainly considering the rigidity of linear guide modules, a ball-screw-feeding spindle is modeled by a mass-spring system. The contact stiffness of rolling interfaces in linear guide modules is accurately calculated according to the Hertzian theory. Next, a mathematical model is derived using the Lagrange method. The presented model is verified by conducting modal experiments. It is found that the simulated results correspond closely with the experimental data. In order to show the applicability of the proposed mathematical model, parameter-dependent dynamics of the feeding carriage of the spindle is investigated. The work will contribute to the vibration prediction of spindles.

  12. Microstructure and mechanical properties of nanocrystalline high strength Al-Mg-Si (AA6061) alloy by high energy ball milling and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Jatinkumar Kumar [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Sivaprahasam, D. [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005 (India); Seetharama Raju, K. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Subramanya Sarma, V., E-mail: vsarma@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India)

    2009-12-15

    In the present paper, the microstructure and mechanical properties of nanostructured Al-Mg-Si based AA6061 alloy obtained by high energy ball milling and spark plasma sintering were reported. Gas atomized microcrystalline powder of AA6061 alloy was ball milled under wet condition at room temperature to obtain nanocrystalline powder with grain size of {approx}30 nm. The nanocrystalline powder was consolidated to fully dense compacts by spark plasma sintering (SPS) at 500 deg. C. The grain size after SPS consolidation was found to be {approx}85 nm. The resultant SPS compacts exhibited microhardness of 190-200 HV{sub 100g}, compressive strength of {approx}800 MPa and strain to fracture of {approx}15%.

  13. Investigation of physical properties and stability of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems prepared by quench cooling, coprecipitation and ball milling

    DEFF Research Database (Denmark)

    Lim, Ai Wei; Löbmann, Korbinian; Grohganz, Holger

    2016-01-01

    OBJECTIVES: The objective was to characterize the structural behaviour of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems (1 : 1 molar ratio) prepared by quench cooling, co-evaporation and ball milling. METHODS: Powder X-ray diffraction (PXRD) and DSC were used to characterise...... by quench cooling (ln τ(β) = 2.4) and co-evaporation (ln τ(β) = 2.5). In contrast, molecular mobility of the naproxen-cimetidine samples followed the order co-evaporation (ln τ(β) = 0.8), quench cooling (ln τ(β) = 1.6) and ball milling (ln τ(β) = 1.8). CONCLUSION: The estimated relaxation times by the DSC...

  14. Correlation of gas sensitivite properties with microstructure of Fe2O3-SnO2 ceramics prepared by high energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lu, S.W.; Zhou, Y.X.

    1997-01-01

    A remarkable gas sensitivity to ethnaol gas has been observed in nanostructured Fe2O3-SnO2 materials with a composition of 6.4 mol% SnO2 prepared by high energy ball milling. The microstructure of the materials has been examined by x-ray diffraction (XRD) and Mossbauer spectroscopy. It was found ...... that tin in the hematite phase plays an important role in high gas sensitivity....

  15. Comparison of particle sizes between 238PuO2 before aqueous processing, after aqueous processing, and after ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Mulford, Roberta Nancy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-06

    Particle sizes determined for a single lot of incoming Russian fuel and for a lot of fuel after aqueous processing are compared with particle sizes measured on fuel after ball-milling. The single samples of each type are believed to have particle size distributions typical of oxide from similar lots, as the processing of fuel lots is fairly uniform. Variation between lots is, as yet, uncharacterized. Sampling and particle size measurement methods are discussed elsewhere.

  16. Stainless-Steel Ball-Milling Method for Hydro-/Deutero-genation using H2O/D2O as a Hydrogen/Deuterium Source.

    Science.gov (United States)

    Sawama, Yoshinari; Kawajiri, Takahiro; Niikawa, Miki; Goto, Ryota; Yabe, Yuki; Takahashi, Tohru; Marumoto, Takahisa; Itoh, Miki; Kimura, Yuuichi; Monguchi, Yasunari; Kondo, Shin-ichi; Sajiki, Hironao

    2015-11-01

    A one-pot continuous-flow method for hydrogen (deuterium) generation and subsequent hydrogenation (deuterogenation) was developed using a stainless-steel (SUS304)-mediated ball-milling approach. SUS304, especially zero-valent Cr and Ni as constituents of the SUS304, and mechanochemical processing played crucial roles in the development of the reactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. A comparison between different X-ray diffraction line broadening analysis methods for nanocrystalline ball-milled FCC powders

    Energy Technology Data Exchange (ETDEWEB)

    Soleimanian, V. [Shahrekord University, Department of Physics, Faculty of Sciences, P.O. Box 115, Shahrekord (Iran, Islamic Republic of); Shahrekord University, Nanotechnology Research Center, Shahrekord (Iran, Islamic Republic of); Mojtahedi, M. [Pooya Gharb Branch of University of Applied Science and Technology, Department of Materials Engineering, Kermanshah (Iran, Islamic Republic of)

    2015-06-15

    The microstructural characteristics of aluminum, copper and nickel powders are investigated using different X-ray diffraction line broadening analysis approaches. Prior to analysis, the powders were ball-milled to produce a nanocrystalline structure with high density of probable types of lattice defects. A variety of methods, including Scherrer, Williamson-Smallman, Williamson-Hall, Warren-Averbach, modified Williamson-Hall, modified Warren-Averbach, Rietveld refinement and whole powder pattern modeling (WPPM) approaches are applied. In this way, microstructural characteristics such as crystallite size, microstrain, dislocation density, effective outer cut-off radius of dislocations and the probability of twining and stacking faults are calculated. On the other hand, the results of conventional and advanced line broadening analysis methods are compared. It is revealed that the density of linear and planar defects in the mechanically deformed aluminum powder is significantly smaller than that of copper and nickel, as well as the level of anisotropic strain broadening. Moreover, the WPPM procedure provided a better profile fitting with more accurate results. (orig.)

  18. Investigation of physical properties and stability of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems prepared by quench cooling, coprecipitation and ball milling.

    Science.gov (United States)

    Lim, Ai Wei; Löbmann, Korbinian; Grohganz, Holger; Rades, Thomas; Chieng, Norman

    2016-01-01

    The objective was to characterize the structural behaviour of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems (1 : 1 molar ratio) prepared by quench cooling, co-evaporation and ball milling. Powder X-ray diffraction (PXRD) and DSC were used to characterise the samples. Structural relaxation (i.e. molecular mobility) behaviour was obtained from the Kohlrausch-Williams-Watts (KWW) relationship. A glass transition temperature (Tg ), on average 20 °C higher than the predicted Tg (calculated from the Fox equation), was observed in all samples. The structural relaxation was dependent on the preparative methods. At a storage temperature of 40 °C, a comparatively higher molecular mobility was observed in indomethacin-cimetidine samples prepared by ball milling (ln τ(β) = 0.8), while similar molecular mobility was found for the same sample prepared by quench cooling (ln τ(β) = 2.4) and co-evaporation (ln τ(β) = 2.5). In contrast, molecular mobility of the naproxen-cimetidine samples followed the order co-evaporation (ln τ(β) = 0.8), quench cooling (ln τ(β) = 1.6) and ball milling (ln τ(β) = 1.8). The estimated relaxation times by the DSC-KWW method suggest that different preparative methods resulted in a variation of structural characteristics. Despite the differences in molecular mobility, all sample remained co-amorphous for up to 7 months. © 2015 Royal Pharmaceutical Society.

  19. Effect of ball-milling and shot-peening on Zr{sub 55}Al{sub 10}Ni{sub 5}Cu{sub 30} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Tokujiro [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)]. E-mail: toku@imr.tohoku.ac.jp; Takahashi, Tsuyoshi [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kimura, Hisamichi [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Inoue, Akihisa [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2007-03-14

    Effect of ball-milling and shot-peening on a metallic glass Zr{sub 55}Al{sub 10}Ni{sub 5}Cu{sub 30}, which possesses a large supercooled liquid region, has been investigated by means of differential scanning calorimetry, x-ray diffractometry and transmission electron microscopy. Metallic glassy ribbons, powders and plates were prepared by melt-spinning, gas-atomizing and mold-clamp casting techniques, respectively. No structural changes were observed in both the ribbon and powder specimens by ball-milling for around 100 h; however, the powder specimens were crystallized by Fe contamination when they were ball-milled for 540 h. No structural evolution was also observed when the plate specimens were subjected to shot-peening, while crystallized plate specimens were easily amorphized by mild and short period shot-peening. These results imply high phase stability of the Zr{sub 55}Al{sub 10}Ni{sub 5}Cu{sub 30} metallic glass against deformation.

  20. Mechanical ball-milling preparation of fullerene/cobalt core/shell nanocomposites with high electrochemical hydrogen storage ability.

    Science.gov (United States)

    Bao, Di; Gao, Peng; Shen, Xiande; Chang, Cheng; Wang, Longqiang; Wang, Ying; Chen, Yujin; Zhou, Xiaoming; Sun, Shuchao; Li, Guobao; Yang, Piaoping

    2014-02-26

    The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today's development of hydrogen economy. Because of the special honeycomb structures and excellent physical and chemical characters, fullerenes have been extensively considered as ideal materials for hydrogen storage materials. To take the most advantage of its distinctive symmetrical carbon cage structure, we have uniformly coated C60's surface with metal cobalt in nanoscale to form a core/shell structure through a simple ball-milling process in this work. The X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, high-solution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDX) elemental mappings, and X-ray photoelectron spectroscopy (XPS) measurements have been conducted to evaluate the size and the composition of the composites. In addition, the blue shift of C60 pentagonal pinch mode demonstrates the formation of Co-C chemical bond, and which enhances the stability of the as-obtained nanocomposites. And their electrochemical experimental results demonstrate that the as-obtained C60/Co composites have excellent electrochemical hydrogen storage cycle reversibility and considerably high hydrogen storage capacities of 907 mAh/g (3.32 wt % hydrogen) under room temperature and ambient pressure, which is very close to the theoretical hydrogen storage capacities of individual metal Co (3.33 wt % hydrogen). Furthermore, their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible C60/Co↔C60/Co-Hx reaction is the dominant cycle process.

  1. Structural and Magnetic Properties Evolution of Co-Nd Substituted M-type Hexagonal Strontium Ferrites Synthesized by Ball-Milling-Assisted Ceramic Process

    Science.gov (United States)

    Chen, Wen; Wu, Wenwei; Zhou, Chong; Zhou, Shifang; Li, Miaoyu; Ning, Yu

    2017-12-01

    M-type hexagonal Sr1-x Co x Nd x Fe12-x O19 (x = 0, 0.08, 0.16, and 0.24) has been synthesized by ball milling, followed by calcination in air. The calcined products have been characterized by x-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra, and vibrating sample magnetometry. XRD and SEM analyses confirm the formation of M-type Sr hexaferrite with platelet-like morphology when Sr1-x Co x Nd x Fe12-x O19 (x = 0, 0.08, 0.16, and 0.24) precursors are calcined at 950°C in air for 2.5 h. Lattice parameters "a" and "c" values of Sr1-x Co x Nd x Fe12-x O19 reflect a very small variation after doping of Nd3+ and Co2+ ions. Average crystallite size of Sr1-x Co x Nd x Fe12-x O19 sample, calcined at 1150°C, decreased obviously after doping of Co2+ and Nd3+ ions. This is because the bond energy of Nd3+-O2- is much larger than that of Sr2+-O2-. Magnetic characterization indicates that all the samples exhibit good magnetic properties. Substitution of Sr2+ and Fe3+ ions by Nd3+ and Co2+ ions can improve the specific saturation magnetizations and remanence of Sr1-x Co x Nd x Fe12-x O19. Sr0.84Co0.16Nd0.16Fe11.84O19, calcined at 1050°C, has the highest specific saturation magnetization value (74.75 ± 0.60 emu/g), remanence (45.15 ± 0.32 emu/g), and magnetic moment (14.34 ± 0.11 μ B); SrFe12O19, calcined at 1150°C, has the highest coercivity value (4037.01 ± 42.39 Oe). These magnetic parameters make this material a promising candidate for applications such as high-density magnetic recording and microwave absorbing materials.

  2. A handy-motion driven, frequency up-converted hybrid vibration energy harvester using PZT bimorph and nonmagnetic ball

    Science.gov (United States)

    Halim, M. A.; Cho, H. O.; Park, J. Y.

    2014-11-01

    We have presented a frequency up-converted hybrid type (Piezoelectric and Electromagnetic) vibration energy harvester that can be used in powering portable and wearable smart devices by handy motion. A transverse impact mechanism has been employed for frequency up-conversion. Use of two transduction mechanisms increases the output power as well as power density. The proposed device consists of a non-magnetic spherical ball (freely movable at handy motion frequency) to impact periodically on the parabolic top of a piezoelectric (PZT) cantilevered mass by sliding over it, allowing it to vibrate at its higher resonant frequency and generates voltage by virtue of piezoelectric effect. A magnet attached to the cantilever vibrates along with it at the same frequency and a relative motion between the magnet and a coil placed below it, induces emf voltage across the coil terminals as well. A macro-scale prototype of the harvester has been fabricated and tested by handy motion. With an optimum magnet-coil overlap, a maximum 0.98mW and 0.64mW peak powers have been obtained from the piezoelectric and the electromagnetic transducers of the proposed device while shaken, respectively. It offers 84.4μWcm-3 peak power density.

  3. Tool wear in terms of vibration effects in milling medium-density fibreboard with an industrial robot

    Energy Technology Data Exchange (ETDEWEB)

    Tratar, Janez; Pusavec, Franci; Kopac, Janez [University of Ljubljana, Askerceva (Slovenia)

    2014-11-15

    Machining with robots represents a promising, highly flexible and cost effective alternative to standard machining and hand labour applications when machining mid tolerance soft material end products. One of the most challenging issues is to know the vibration characteristics in milling with the robots which greatly affect tool life. In general the technological bases of tool life expectancy while milling with robot arms are not available or studied. That's why the purpose of this paper is to investigate the influence of attained vibrations analysis during the milling process and correlated tool wear. Primarily the study is focused on tool wear according to the distance between the milling position and the robot's base. Results show that increasing distance between the robot's base and the milling position significantly affects tool wear because of the attained vibrations in proportion to the increasing distance respectively. Tool wear has also proved to be greater in comparison to machining with CNC machine and applicable new information for woodworking industry.

  4. Microstructural evolution during high energy ball milling of Fe2O3-SiO2 powders

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Zhou, Y.X.; Mørup, Steen

    1996-01-01

    of 15 nm have formed and no reaction between alpha-Fe2O3 and SiO2 is found in the two types of milling containers. This demonstrates that the high energy mechanical milling technique is able to prepare a dispersion of ultrafine alpha-Fe2O3 particles. After extended milling in the open container all iron...

  5. Fibrillation of Aspen by Alkaline Cold Pre-treatment and Vibration Milling

    Directory of Open Access Journals (Sweden)

    Kärt KÄRNER

    2016-09-01

    Full Text Available In this article an attempt to fibrillate aspen bleached chemi-thermo mechanical pulp (BCTMP fibre in an environmentally friendly way is reported. The effects of various NaOH, KOH, urea and ethanol aqueous solutions at lowered temperature were tested for pre-treatment. The pre-treatment was followed by vibration milling aiming to peel off outer cell wall layers and to fibrillate S2 layer of the aspen wood fibre. The effects of the treatments were evaluated by scanning electron microscopy (SEM. The results show that it is possible to fibrillate BCTMP aspen fibres by using alkaline aqueous solutions at low temperatures followed by a mechanical treatment. A strong dependence on fibrillation of cellulose on temperature, time and alkali concentration was established.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.7412

  6. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching.

    Science.gov (United States)

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon

    2015-04-01

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na2CO3, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na2CO3, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4M HCl, 100°C and pulp density of 20g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Influence of vegetable based cutting fluids on cutting force and vibration signature during milling of aluminium metal matrix composites

    Directory of Open Access Journals (Sweden)

    S. Shankar

    2017-03-01

    Full Text Available Due to the environmental and health issues, there is an enormous requirement for developing the novel cutting fluids (CFs. The vegetable based cutting fluid (VBCFs doesn’t affect the environment, diminish the harmful effects to the operator and also enhance the machining performances such as surface roughness, tool life, minimum vibration and cutting forces. In this work, the performances of four different VBCFs like palm, coconut, sunflower, soya bean oils, and a commercial type of CFs were considered to analyze the influence of cutting fluids while measuring the cutting force and vibration signatures during milling of 7075–T6 hybrid aluminium metal matrix composite with carbide insert tool. The experiments were conducted in CNC L-MILL 55 vertical machining center, with milling tool dynamometer to measure the cutting force and a tri-axial accelerometer to measure the vibration signals. The flow rate of the VBCFs were maintained at a constant rate and the results were compared with a commercial cutting fluid. The obtained result shows that palm oil suits better than the other vegetable based cutting fluids in terms of minimum cutting force requirement and minimum vibration. Also, the experimental result shows that the cutting fluid was one of the important parameter needs to be considered which influences the cutting force and vibration signals.

  8. Nanostructuration of metals via spark plasma sintering using activated powder obtained by ball-milling: Impact on the strain-hardening mechanisms

    Science.gov (United States)

    de la Cruz, Lucía García; Flipon, Baptiste; Keller, Clément; Martinez, Mayerling; Hug, Eric

    2017-10-01

    Powder metallurgy is a good option when coupled with pressure as a method to obtain nanostructured materials (NsM). The samples obtained by these means are nearly fully dense specimens that present low internal stresses. In this work, nickel is chosen to study the possibilities of nanostructuration via Spark Plasma Sintering (SPS) of ball-milled powders. The enhancement of the mechanical properties of the sintered samples are studied and compared with the results obtained for 316L austenitic stainless steel in a previous work.

  9. Solvent-free and time-efficient Suzuki–Miyaura reaction in a ball mill: the solid reagent system KF–Al2O3 under inspection

    Directory of Open Access Journals (Sweden)

    Franziska Bernhardt

    2010-01-01

    Full Text Available Although a plethora of synthetic procedures mediated by KF-loaded aluminas is available in the literature, there is almost no data concerning the influence of parameters such as alumina modification or KF-loading on experimental results. Hence, the Pd-catalyzed, solvent-free Suzuki–Miyaura reaction was chosen as model reaction to investigate the effect of the above mentioned parameters on the results of coupling reactions. The results from ball milling experiments led to the conclusion that self-prepared and commercially available KF–Al2O3 differ in water content. The higher the residual water content, the higher are the product yields.

  10. Effect of soya milk on nutritive, antioxidative, reological and textural properties of chocolate produced in a ball mill

    Directory of Open Access Journals (Sweden)

    Zarić Danica B.

    2011-01-01

    Full Text Available Chocolate is a complex rheological system in which non-fat cocoa particles and sugar particles are enveloped by crystal matrix of cocoa butter. Physical properties of chocolate depend on ingredient composition, method of production and properly performed pre-crystallization phase. In this work, chocolate was produced in an unconventional way, i.e. in a ball mill applying variable refining time (30, 60 and 90 min and pre-crystallization temperature in chocolate masses (26, 28 and 30⁰C. Two types of chocolate were produced: chocolate with 20% of powdered cow’s milk (R1 and chocolate with 20% of soya milk powder (R2. The quality of chocolate was followed by comparing nutritive composition, 23 polyphenol content, hardness of chocolate, solid triglyceride content (SFC and rheological parameters (Casson yield flow (Pa, Casson viscosity (Pas, the area of the thixotropic loop, elastic modulus and creep curves. The aim of this paper is determining changes caused by replacing cow’s milk with soya milk powder in respect of nutritive, rheological and sensory properties, as well as defining optimal parameters: precrystallization temperature and refining time of soya milk chocolate in order to obtain suitable sensory and physical properties identical to those of milk chocolate mass. The results show that replacing powdered cow’s milk with soya milk powder affects the increase in nutritive value of soya milk chocolate. R2 chocolate mass showed the increase in essential amino acids and fatty acids. This chocolate mass also showed the increase in total polyphenols by 28.1% comparing to R1 chocolate mass. By comparing viscosity, yield stress, shear stress and the area of the thixotropic loop, it can be observed that R1 chocolate mass represents a more organized and simpler system than the mass with soya milk (R2, as it shows lower values for all the above mentioned parameters, regardless of the refining time and pre-crystallization temperature

  11. Heterogeneous sono-Fenton-like process using martite nanocatalyst prepared by high energy planetary ball milling for treatment of a textile dye.

    Science.gov (United States)

    Dindarsafa, Mahsa; Khataee, Alireza; Kaymak, Baris; Vahid, Behrouz; Karimi, Atefeh; Rahmani, Amir

    2017-01-01

    High energy planetary ball milling was applied to prepare sono-Fenton nanocatalyst from natural martite (NM). The NM samples were milled for 2-6h at the speed of 320rpm for production of various ball milled martite (BMM) samples. The catalytic performance of the BMMs was greater than the NM for treatment of Acid Blue 92 (AB92) in heterogeneous sono-Fenton-like process. The NM and the BMM samples were characterized by XRD, FT-IR, SEM, EDX and BET analyses. The particle size distribution of the 6h-milled martite (BMM3) was in the range of 10-90nm, which had the highest surface area compared to the other samples. Then, the impact of main operational parameters was investigated on the process. Complete removal of the dye was obtained at the desired conditions including initial pH 7, 2.5g/L BMM3 dosage, 10mg/L AB92 concentration, and 150W ultrasonic power after 30min of treatment. The treatment process followed pseudo-first order kinetic. Environmentally-friendly modification of the NM, low leached iron amount and repeated application at milder pH were the significant benefits of the BMM3. The GC-MS was successfully used to identify the generated intermediates. Eventually, an artificial neural network (ANN) was applied to predict the AB92 removal efficiency based upon the experimental data with a proper correlation coefficient (R(2)=0.9836). Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Lignocellulose fermentation and residual solids characterization for senescent switchgrass fermentation by Clostridium thermocellum in the presence and absence of continuous in situ ball-milling

    Energy Technology Data Exchange (ETDEWEB)

    Balch, Michael L.; Holwerda, Evert K.; Davis, Mark F.; Sykes, Robert W.; Happs, Renee M.; Kumar, Rajeev; Wyman, Charles E.; Lynd, Lee R.

    2017-04-12

    Milling during lignocellulosic fermentation, henceforth referred to as cotreatment, is investigated as an alternative to thermochemical pretreatment as a means of enhancing biological solubilization of lignocellulose. We investigate the impact of milling on soluble substrate fermentation by Clostridium thermocellum with comparison to yeast, document solubilization for fermentation of senescent switchgrass with and without ball milling, and characterize residual solids. Soluble substrate fermentation by C. thermocellum proceeded readily in the presence of continuous ball milling but was completely arrested for yeast. Total fractional carbohydrate solubilization achieved after fermentation of senescent switchgrass by C. thermocellum for 5 days was 0.45 without cotreatment or pretreatment, 0.81 with hydrothermal pretreatment (200 degrees C, 15 minutes, severity 4.2), and 0.88 with cotreatment. Acetate and ethanol were the main fermentation products, and were produced at similar ratios with and without cotreatment. Analysis of solid residues was undertaken using molecular beam mass spectrometry (PyMBMS) and solid-state nuclear magnetic resonance spectroscopy (NMR) in order to provide insight into changes in plant cell walls during processing via various modes. The structure of lignin present in residual solids remaining after fermentation with cotreatment appeared to change little, with substantially greater changes observed for hydrothermal pretreatment - particularly with respect to formation of C-C bonds. The observation of high solubilization with little apparent modification of the residue is consistent with cotreatment enhancing solubilization primarily by increasing the access of saccharolytic enzymes to the feedstock, and C. thermocellum being able to attack all the major linkages in cellulosic biomass provided that these linkages are accessible.

  13. A Primer on Vibrational Ball Bearing Feature Generation for Prognostics and Diagnostics Algorithms

    Science.gov (United States)

    2015-03-01

    problems appear in ultrasonic frequencies ranging from approximately 20–60 KHz. An approximate frequency span for the high frequency region is 2 to 120 KHz...processing, radar , and sonar applications. Many of these techniques are applicable to the analysis of the vibrational data from a bearing. These

  14. Synthesis of stoichiometric Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles by high-energy ball milling and thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, B.F.; Morales, M.A.; Bohn, F.; Carriço, A.S. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Medeiros, S.N. de, E-mail: sndemedeiros@gmail.com [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Dantas, A.L. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, 59610-210 Mossoró, RN (Brazil)

    2016-05-01

    We report the synthesis of Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles by high-energy ball milling and thermal annealing from α-Fe{sub 2}O{sub 3} and CaCO{sub 3}. Magnetization measurements, Mössbauer and X-ray spectra reveal that annealing at high temperatures leads to better quality samples. Our results indicate nanoparticles produced by 10 h high-energy ball milling and thermal annealing for 2 h at 1100 °C achieve improved stoichiometry and the full weak ferromagnetic signal of Ca{sub 2}Fe{sub 2}O{sub 5}. Samples annealed at lower temperatures show departure from stoichiometry, with a higher occupancy of Fe{sup 3+} in octahedral sites, and a reduced magnetization. Thermal relaxation for temperatures in the 700–1100 °C range is well represented by a Néel model, assuming a random orientation of the weak ferromagnetic moment of the Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles.

  15. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching

    Energy Technology Data Exchange (ETDEWEB)

    Swain, Basudev, E-mail: swain@iae.re.kr; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo, E-mail: kspark@iae.re.kr; Lee, Chan Gi; Hong, Hyun Seon, E-mail: hshong@iae.re.kr

    2015-04-15

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na{sub 2}CO{sub 3}, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na{sub 2}CO{sub 3}, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4 M HCl, 100 °C and pulp density of 20 g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. - Highlights: • Simplest process for treatment of GaN an LED industry waste developed. • The process developed recovers gallium from waste LED waste dust. • Thermal analysis and phase properties of GaN to Ga{sub 2}O{sub 3} and GaN to NaGaO{sub 2} revealed. • Solid-state chemistry involved in this process reported. • Quantitative leaching of the GaN was achieved.

  16. Vibrating vaginal balls to improve pelvic floor muscle performance in women after childbirth: a protocol for a randomised controlled feasibility trial.

    Science.gov (United States)

    Oblasser, Claudia; McCourt, Christine; Hanzal, Engelbert; Christie, Janice

    2016-04-01

    This paper presents a feasibility trial protocol the purpose of which is to prepare for a future randomised controlled trial to determine the effectiveness of vibrating vaginal pelvic floor training balls for postpartum pelvic floor muscle rehabilitation. Vibrating vaginal pelvic floor training balls are available in Austria to enhance women's pelvic floor muscles and thus prevent or treat urinary incontinence and other pelvic floor problems following childbirth. Nonetheless, there is currently little empirical knowledge to substantiate their use or assess their relative effectiveness in comparison to current standard care, which involves pelvic floor muscle exercises. Single blind, randomised controlled feasibility trial with two parallel groups. It is planned to recruit 56 postpartum women in Vienna, who will be randomised into one of two intervention groups to use either vibrating vaginal balls or a comparator pelvic floor muscle exercises for 12 weeks. As this is a feasibility study, study design features (recruitment, selection, randomisation, intervention concordance, data collection methods and tools) will be assessed and participants' views and experiences will be surveyed. Tested outcome measures, collected before and after the intervention, will be pelvic floor muscle performance as reported by participants and measured by perineometry. Descriptive and inferential statistics and content analysis will serve the preparation of the future trial. The results of this feasibility trial will inform the design and conduct of a full randomised controlled trial and provide insight into the experiences of women regarding the interventions and study participation. © 2015 John Wiley & Sons Ltd.

  17. Fabrication of Fe1.1Se0.5Te0.5 bulk by a high energy ball milling technique

    Science.gov (United States)

    Liu, Jixing; Li, Chengshan; Zhang, Shengnan; Feng, Jianqing; Zhang, Pingxiang; Zhou, Lian

    2017-11-01

    Fe1.1Se0.5Te0.5 superconducting bulks were successfully synthesized by a high energy ball milling (HEBM) aided sintering technique. Two advantages of this new technique have been revealed compared with traditional solid state sintering method. One is greatly increased the density of sintered bulks. It is because the precursor powders with β-Fe(Se, Te) and δ-Fe(Se, Te) were obtained directly by the HEBM process and without formation of liquid Se (and Te), which could avoid the huge volume expansion. The other is the obvious decrease of sintering temperature and dwell time due to the effective shortened length of diffusion paths. The superconducting critical temperature Tc of 14.2 K in our sample is comparable with those in previous reports, and further optimization of chemical composition is on the way.

  18. Investigating the Possibility to Reduce the Residual Stress Level in 2.5D Cutting Using Titanium Coated Carbide Ball End Mill

    Directory of Open Access Journals (Sweden)

    N. Masmiati

    2014-01-01

    Full Text Available End milling is a multipoint cutting process in which material is removed from a workpiece by a rotating tool. It is widely used in cutting 2.5D profiles such as point-to-point, contouring, and pocketing operations. 2.5D machining possesses the capability to translate in all 3 axes but can perform the cutting operation in only 2 of the 3 axes at a time. This study focuses on optimizing the cutting parameters, such as machined surface inclinationangle, axial depth of cut, spindle speed, and feed rate for better surface integrity, namely, microhardness, residual stress, and microstructure in 2.5D cutting utilizing a titanium-coated carbide ball end mill. An optimization method known as Taguchi optimization, which includes planning, conducting, and analyzing results of matrix experiments, was used in order to achieve the best cutting parameter level. Data analysis was conducted using signal-to-noise (S/N and target performance measurement (TPM response analysis and analysis of variance (Pareto ANOVA. The optimum condition results obtained through analysis show improvements in microhardness of about 0.7%, residual stress in the feed direction of about 18.6%, and residual stress in the cutting direction of about 15.4%.

  19. Exfoliation of graphite with triazine derivatives under ball-milling conditions: preparation of few-layer graphene via selective noncovalent interactions.

    Science.gov (United States)

    León, Verónica; Rodriguez, Antonio M; Prieto, Pilar; Prato, Maurizio; Vázquez, Ester

    2014-01-28

    A ball-milling treatment can be employed to exfoliate graphite through interactions with commercially available melamine under solid conditions. This procedure allows the fast production of relatively large quantities of material with a low presence of defects. The milling treatment can be modulated in order to achieve graphene flakes with different sizes. Once prepared, the graphene samples can be redispersed in organic solvents, water, or culture media, forming stable dispersions that can be used for multiple purposes. In the present work, we have screened electron-rich benzene derivatives along with triazine derivatives in their respective ability to exfoliate graphite. The results suggest that the formation of a hydrogen-bonding network is important for the formation of multipoint interactions with the surfaces of graphene, which can be used for the exfoliation of graphite and the stabilization of graphene in different solvents. Aminotriazine systems were found to be the best partners in the preparation and stabilization of graphene layers in different solvents, while the equivalent benzene derivatives did not show comparable exfoliation ability. Computational studies have also been performed to rationalize the experimental results. The results provide also the basis for further work in the preparation of noncovalently modified graphene, where derivatives of aminotriazines can be designed to form extensive hydrogen-bond 2D networks on the graphene surface with the aim of manipulating their electronic and chemical properties.

  20. Analyses of the most influential factors for vibration monitoring of planetary power transmissions in pellet mills by adaptive neuro-fuzzy technique

    Science.gov (United States)

    Milovančević, Miloš; Nikolić, Vlastimir; Anđelković, Boban

    2017-01-01

    Vibration-based structural health monitoring is widely recognized as an attractive strategy for early damage detection in civil structures. Vibration monitoring and prediction is important for any system since it can save many unpredictable behaviors of the system. If the vibration monitoring is properly managed, that can ensure economic and safe operations. Potentials for further improvement of vibration monitoring lie in the improvement of current control strategies. One of the options is the introduction of model predictive control. Multistep ahead predictive models of vibration are a starting point for creating a successful model predictive strategy. For the purpose of this article, predictive models of are created for vibration monitoring of planetary power transmissions in pellet mills. The models were developed using the novel method based on ANFIS (adaptive neuro fuzzy inference system). The aim of this study is to investigate the potential of ANFIS for selecting the most relevant variables for predictive models of vibration monitoring of pellet mills power transmission. The vibration data are collected by PIC (Programmable Interface Controller) microcontrollers. The goal of the predictive vibration monitoring of planetary power transmissions in pellet mills is to indicate deterioration in the vibration of the power transmissions before the actual failure occurs. The ANFIS process for variable selection was implemented in order to detect the predominant variables affecting the prediction of vibration monitoring. It was also used to select the minimal input subset of variables from the initial set of input variables - current and lagged variables (up to 11 steps) of vibration. The obtained results could be used for simplification of predictive methods so as to avoid multiple input variables. It was preferable to used models with less inputs because of overfitting between training and testing data. While the obtained results are promising, further work is

  1. Effect of Ball-Milling on Magnetic Properties of Uniaxial Nanocrystalline SmNi_2 Fe Compound

    Science.gov (United States)

    Nouri, K.; Bouzidi, W.; Jemmali, M.; Hentech, I.; Dhahri, E.; Bessais, L.

    2018-02-01

    We report an interesting structural and nanostructural correlation to the Curie temperature and coercivity, respectively. The effect of Ni substitution and magnetocaloric effect (MCE) response for the uniaxial nanocrystalline SmNi_2Fe compound was demonstrated. The nanocrystalline SmNi2Fe(SmNi_2Fe) powder has been synthesized by mechanical milling for the first time. The nanocrystalline SmNi_2Fe powder has been synthesized by mechanical milling. The structural properties have been studied by x-ray diffraction and have been refined with the Rietveld method. This analysis reveals that the samples crystallize in the rhombohedral PuNi_3-type structure (R\\bar{3}m-space group). The Curie temperature of SmNi_2Fe material is about 450 K. It is a direct measure of the exchange interaction, which is the origin of ferromagnetic phase transition. This interaction depends markedly on the interatomic distance. The magnetic entropy change Δ SM, as well as the relative cooling power around the second-order magnetic transition and the Arrott plots for the compound have been reported. It was estimated from isothermal magnetization curves, and it decreases with the increase of Fe content from 2.3 J/kg K (x = 0) to 0.6 J/kg K (x = 0.8) at 50 kOe. The compound presents high coercivity exceeding 12 kOe at room temperature, obtained based on the optimization of SmNi_2Fe nanostructure. The objective of this optimization is to obtain a homogeneous nanostructure developed by the mechanical milling process, subsequent annealing and to the high uniaxial magnetocrystalline anisotropy.

  2. Effect of Ball-Milling on Magnetic Properties of Uniaxial Nanocrystalline SmNi_2 Fe Compound

    Science.gov (United States)

    Nouri, K.; Bouzidi, W.; Jemmali, M.; Hentech, I.; Dhahri, E.; Bessais, L.

    2017-10-01

    We report an interesting structural and nanostructural correlation to the Curie temperature and coercivity, respectively. The effect of Ni substitution and magnetocaloric effect (MCE) response for the uniaxial nanocrystalline SmNi_2Fe compound was demonstrated. The nanocrystalline SmNi2Fe(SmNi_2Fe ) powder has been synthesized by mechanical milling for the first time. The nanocrystalline SmNi_2Fe powder has been synthesized by mechanical milling. The structural properties have been studied by x-ray diffraction and have been refined with the Rietveld method. This analysis reveals that the samples crystallize in the rhombohedral PuNi_3 -type structure (R\\bar{3}m -space group). The Curie temperature of SmNi_2Fe material is about 450 K. It is a direct measure of the exchange interaction, which is the origin of ferromagnetic phase transition. This interaction depends markedly on the interatomic distance. The magnetic entropy change Δ SM , as well as the relative cooling power around the second-order magnetic transition and the Arrott plots for the compound have been reported. It was estimated from isothermal magnetization curves, and it decreases with the increase of Fe content from 2.3 J/kg K (x = 0 ) to 0.6 J/kg K (x = 0.8 ) at 50 kOe. The compound presents high coercivity exceeding 12 kOe at room temperature, obtained based on the optimization of SmNi_2Fe nanostructure. The objective of this optimization is to obtain a homogeneous nanostructure developed by the mechanical milling process, subsequent annealing and to the high uniaxial magnetocrystalline anisotropy.

  3. Dispersion of silicon carbide nanoparticles in a AA2024 aluminum alloy by a high-energy ball mill

    Energy Technology Data Exchange (ETDEWEB)

    Carreño-Gallardo, C.; Estrada-Guel, I. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología-Chihuahua, Miguel de Cervantes No. 120, CP 31109, Chihuahua, México (Mexico); López-Meléndez, C. [Universidad La Salle Chihuahua, Prol. Lomas de Majalca No. 11201, CP 31020, Chihuahua, México (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología-Chihuahua, Miguel de Cervantes No. 120, CP 31109, Chihuahua, México (Mexico)

    2014-02-15

    Highlights: • Synthesis of 2024-SiC{sub NP} nanocomposite by mechanical milling process. • SiC nanoparticles improved mechanical properties of aluminum alloy 2024 matrix. • A homogeneous distribution of SiC nanoparticles were observed in the matrix • Compressive and hardness properties of the composite are improved significantly. -- Abstract: Al{sub 2024} alloy was reinforced with silicon carbide nanoparticles (SiC{sub NP}), whose concentration was varied in the range from 0 to 5 wt.%; some composites were synthesized with the mechanical milling (MM) process. Structure and microstructure of the consolidated samples were studied by X-ray diffraction and transmission electron microscopy, while mechanical properties were investigated by compressive tests and hardness measurements. The microstructural evidence shows that SiC{sub NP} were homogeneously dispersed into the Al{sub 2024} alloy using high-energy MM after 2 h of processing. On the other hand, an increase of the mechanical properties (yield stress, maximum strength and hardness) was observed in the synthesized composites as a direct function of the SiC{sub NP} content. In this research several strengthening mechanisms were observed, but the main was the obstruction of dislocations movement by the addition of SiC{sub NP}.

  4. A Mössbauer and magnetic study of ball milled Fe-doped ZnO Powders

    Energy Technology Data Exchange (ETDEWEB)

    Zamora, Ligia E., E-mail: ligia.zamora@correounivalle.edu.co; Paz, J. C.; Piamba, J. F.; Tabares, J. A.; Alcázar, G. A. Pérez [Universidad del Valle, Departamento de física (Colombia)

    2015-06-15

    The structural and magnetic properties of Fe-doped ZnO are reported in this study, as obtained by mechanical alloying from elemental powders of ZnO and Fe. The properties of Zn{sub 0.90}Fe{sub 0.10}O samples alloying while varying the milling time (6, 12, 24 and 36 h) are also reported. The Rietveld refinement of X-ray Diffraction (XRD) patterns revealed that the system presents two structures: the würtzite structure of ZnO and the bcc structure of α-Fe. The Mössbauer spectra show that the samples present three components: a ferromagnetic component, associated with the Fe phase and two paramagnetic components, associated with the Fe atoms, which penetrate inside the ZnO matrix behaving as Fe{sup 3+} and Fe{sup 2+}. The milling time contributes to an increase in the paramagnetic sites, and a solubility limit of the Fe atoms in the ZnO lattice was detected. The VSM measurements at room temperature detected ferromagnetic behavior with a saturation magnetization of 11 emu/g and a coercive field of 330 Oe for the sample alloyed over 24 h. A similar behavior was shown by the other samples.

  5. Flank wear and I-kaz 3D correlation in ball end milling process of Inconel 718

    Directory of Open Access Journals (Sweden)

    M.A.S.M. Tahir

    2015-12-01

    Full Text Available Tool wear may deteriorate the machine product quality due to high surface roughness, dimension exceeding tolerance and also to machine tool itself. Tool wear monitoring system is vital to be used in machining process to achieve high quality of the machined product and at the same time improve the productivity. Nowadays, many monitoring system developed using various sensor and statistical technique to analyze the signals being used. In this paper, I-kaz 3D method is used to analyze cutting force signal in milling process of Inconel 718 for monitoring the status of tool wear in milling process. The results from analyzing cutting force show that I-kaz 3D coefficient has a correlation with cutting tool condition. Tool wear will generate high value of I-kaz 3D coefficient than the sharp cutting tool. Furthermore, the three dimension graphical representation of I-kaz 3D for all cutting condition shown that the degree of scattering data increases with tool wear progression.

  6. The metal-tool contact friction at the ultrasonic vibration drawing of ball-bearing steel wires

    Directory of Open Access Journals (Sweden)

    Susan, Mihai

    1999-12-01

    Full Text Available The friction reversion mechanism during the ultrasonic vibration drawing (UVD of wires has been detailed for the case when the die is located at the oscillation maxima of the waves and actuated parallel to the friction force direction. The decrease of the drawing force for the UVD technology as compared to classical drawing has been explained by means of the intermittent contact in the metal-die forming area. A relationship has been derived for the UVD friction coefficient, μUS that allowed the analytical determination of the drawing force. In the case of the Romanian RUL 1V (AISI 52100 ball bearing steel wires, a good agreement has been found between the analytical and the experimental values of the drawing forces that have decreased, as compared to classical drawing, by more than 5 % for drawing rates lower than 0.66m/s.

    Se hace un análisis pormenorizado del mecanismo de reversión de la fricción al estirado por vibraciones ultrasonoras (EVU de los alambres, para el caso en que la trefiladora está ubicada en los máximos de oscilación de las ondas y activada paralelamente a la dirección de estirado. La disminución de la fuerza de estirado para la tecnología EVU en comparación con el estirado clásico, se ha explicado a través del contacto intermitente en el área de deformación metal-herramienta. Se halló una relación para el coeficiente de fricción EVU, μUS que permitió la determinación analítica de la fuerza de estirado. En el caso de los alambres de acero rumano de rodamientos RUL 1V (AISI 52100 se encontró una justa concordancia entre los valores analítico y experimental de la fuerza de estirado que, en comparación con los de estirado clásico, se encontraron disminuidos en más de un 5 % para velocidades de estirado menores de 0,66m/s.

  7. Studies of superspin glass state and AC-losses in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanoparticles obtained by high-energy ball-milling

    Energy Technology Data Exchange (ETDEWEB)

    Phong, P.T., E-mail: ptphong.nh@khanhhoa.edu.vn [Department of Advanced Materials Chemistry, Dongguk University-Gyeongju, 707 Suckjang-dong, Gyeongbuk, Gyeongju-Si 780-714 (Korea, Republic of); Nha Trang Pedagogic College, 1 Nguyen Chanh Street, Khanh Hoa Province, Nha Trang City (Viet Nam); Manh, D.H. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, Ha Noi City (Viet Nam); Nguyen, L.H. [Nha Trang Pedagogic College, 1 Nguyen Chanh Street, Khanh Hoa Province, Nha Trang City (Viet Nam); Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, Ha Noi City (Viet Nam); Tung, D.K. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, Ha Noi City (Viet Nam); Phuc, N.X., E-mail: phucnx1949@gmail.com [Nha Trang Pedagogic College, 1 Nguyen Chanh Street, Khanh Hoa Province, Nha Trang City (Viet Nam); Lee, I.-J., E-mail: lij@dongguk.ac.kr [Department of Advanced Materials Chemistry, Dongguk University-Gyeongju, 707 Suckjang-dong, Gyeongbuk, Gyeongju-Si 780-714 (Korea, Republic of)

    2014-11-15

    Single-phase perovskite compound La{sub 0.7}Sr{sub 0.3}MnO{sub 3} was synthesized by a high-energy ball milling method. Nanoparticle nature of this manganite with the average particle diameter of 11 nm was revealed from structure and morphology characterizations. The results of ac magnetic susceptibility measurements show that the system can be described as an ensemble of interacting magnetic nanoparticles, which indicates that the dipole–dipole interactions are strong enough to create superspin glass state in the sample. Furthermore, the specific loss power which is exhausted on the irradiation of an ensemble of particles with a magnetic field has been calculated and measured experimentally. - Highlights: • LSMO nanopowder was prepared by the high-energy ball-milling method. • The superspin glass state of LSMO nanopowder was studied. • The SLP has been calculated and measured experimentally.

  8. Analytical Modeling of a Ball Screw Feed Drive for Vibration Prediction of Feeding Carriage of a Spindle

    OpenAIRE

    Lei Zhang; Taiyong Wang; Songling Tian; Yong Wang

    2016-01-01

    An analytical modeling approach for ball screw feed drives is proposed to predict the dynamic behavior of the feeding carriage of a spindle. Mainly considering the rigidity of linear guide modules, a ball-screw-feeding spindle is modeled by a mass-spring system. The contact stiffness of rolling interfaces in linear guide modules is accurately calculated according to the Hertzian theory. Next, a mathematical model is derived using the Lagrange method. The presented model is verified by conduct...

  9. Plasma theory of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Ostapenko, V.I.; Tolpygo, K.B.

    1984-02-01

    The high-energy density inside the ball lightning is due to existence of intense plasma oscillations and high kinetic and potential energy of electron gas which form a pulsating ball vibrating relative to the nearly stationary ionic ball. At sublight velocities of electrons one can neglect the processes of their scattering and recombination. One obtains a relation between parameters of the plasma ball from the condition of equality of excess pressure of ions and that of Madelung forces. The high lifetime of the ball lighting is connected with small Landau damping for the longest wave vibrations.

  10. The grinding behavior of ground copper powder for Cu/CNT nanocomposite fabrication by using the dry grinding process with a high-speed planetary ball mill

    Science.gov (United States)

    Choi, Heekyu; Bor, Amgalan; Sakuragi, Shiori; Lee, Jehyun; Lim, Hyung-Tae

    2016-01-01

    The behavior of ground copper powder for copper-carbon nanotube (copper-CNT) nanocomposite fabrication during high-speed planetary ball milling was investigated because the study of the behavior characteristics of copper powder has recently gained scientific interest. Also, studies of Cu/CNT composites have widely been done due to their useful applications to enhanced, advanced nano materials and components, which would significantly improve the properties of new mechatronics-integrated materials and components. This study varied experimental conditions such as the rotation speed and the grinding time with and without CNTs, and the particle size distribution, median diameter, crystal structure and size, and particle morphology were monitored for a given grinding time. We observed that pure copper powders agglomerated and that the morphology changed with changing rotation speed. The particle agglomerations were observed with maximum experiment conditions (700 rpm, 60 min) in this study of the grinding process for mechanical alloys in the case of pure copper powders because the grinding behavior of Cu/CNT agglomerations was affected by the addition of CNTs. Indeed, the powder morphology and the crystal size of the composite powder could be changed by increasing the grinding time and the rotation speed.

  11. Ball-milled nano-colloids of rare-earth compounds as liquid gain media for capillary optical amplifiers and lasers

    Science.gov (United States)

    Patel, Darayas; Blockmon, Avery; Ochieng, Vanesa; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wesley, Dennis; Sarkisov, Sergey S.; Darwish, Abdalla M.; Sarkisov, Avedik S.

    2017-02-01

    Nano-colloids and nano-crystals doped with ions of rare-earth elements have recently attracted a lot of attention in the scientific community due to their potential applications as biomarkers, fluorescent inks, gain media for lasers and optical amplifiers. Many rare-earth doped materials of different compositions, shapes and size distribution have been prepared by different synthetic methods, such as chemical vapor deposition, sol-gel process, micro-emulsion techniques, gas phase condensation methods, hydrothermal methods and laser ablation. In this paper micro-crystalline powder of the rare-earthdoped compound NaYF4:Yb3+, Er3+ was synthesized using a simple wet process followed by baking in open air. Under 980 nm diode laser excitation strong fluorescence in the 100 nm band around 1531-nm peak was observed from the synthesized micro-powder. The micro-powder was pulverized using a ball mill and prepared in the form of nano-colloids in different liquids. The particle size of the obtained nano-colloids was measured using an atomic force microscope and a dynamic light scatterometer. The size of the nano-particles was close to 100-nm. The nano-colloids were utilized as a filling media in capillary optical amplifiers and lasers. The gain of a 7-cm-long capillary optical amplifier (150-micron inner diameter) was as high as 6 dB at 200 mW pump power. The synthesized nano-colloids and the active optical components using them can be potentially used in optical communication, signal processing, optical computing, and other applications.

  12. In situ Fabrication of Fe-TiB{sub 2} Nanocomposite Powder by Planetary Ball Milling and Subsequent Heat-treatment of FeB and TiH{sub 2} Powder Mixture

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, Xuan-Khoa [Hanoi Uneversity of Science and Technology, Hanoi (Viet Nam); Bae, Sun-Woo; Kim, Ji Soon [University of Ulsan, Ulsan (Korea, Republic of)

    2017-01-15

    Fe-TiB{sub 2} powder was synthesized in-situ by the planetary ball milling and subsequent heat-treatment of an iron boride (FeB) and titanium hydride (TiH{sub 2}) powder mixture. Mechanical activation of the (FeB+TiH{sub 2}) powder mixtures was observed after a milling time of 3 hours at 700 rpm of rotation speed, but activation was not the same after 1 hour milling time. The particle size of the (FeB+ TiH{sub 2}) powder mixture was reduced to the nanometer scale, and each constituent was homogeneously distributed. A sharp exothermic peak was observed at a lower temperature (749 ℃) on the DSC curves for the (FeB+TiH{sub 2}) powder mixture milled for 3 hours, compared to the one milled for 1 hour (774 ℃). These peaks were confirmed to have resulted from the formation reaction of the TiB{sub 2} phase, from Ti and B elements in the FeB. The Fe-TiB{sub 2} composite powder fabricated in situ exhibited only two phases of Fe and TiB{sub 2} with homogeneous distribution. The size of the TiB{sub 2} particulates in the Fe matrix was less than 5 nm.

  13. Moessbauer spectroscopy study of the synthesis of SnFe{sub 2}O{sub 4} by high energy ball milling (HEBM) of SnO and {alpha}-Fe{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Uwakweh, Oswald N C; Perez Moyet, Richard [Department of Engineering Science and Material, University of Puerto Rico-Mayagueez (Puerto Rico); Mas, Rita; Morales, Carolyn [Department of Industrial Engineering, University of Puerto Rico-Mayagueez (Puerto Rico); Vargas, Pedro; Silva, Josue; Rossa, Angel [Department of Mechanical Engineering, University of Puerto Rico-Mayagueez (Puerto Rico); Lopez, Neshma, E-mail: uwakweh@ece.uprm.ed [Department of Chemical Engineering, University of Puerto Rico-Mayagueez (Puerto Rico)

    2010-03-01

    The formation of single phase nanoparticles of spinel structured ferrite, SnFe{sub 2}O{sub 4}, by mechanochemical syntheses using HEBM of stoichiometric amounts of solid SnO and {alpha}-Fe{sub 2}O{sub 3} with acetone as surfactant was achieved progressively as function of ball milling time. Single phase SnFe{sub 2}O{sub 4} formation commenced from five hours of continuous ball milling, and reached completion after 22 hours, thereby yielding a material with a lattice parameter of 8.543 A, and particle size of 10.91 nm. The coercivity was 4.44 mT, magnetic saturation value of 17.75 Am{sup 2}/kg, and remanent magnetizations of 1.50 Am{sup 2}/kg, correspondingly. The nanosized particles exhibited superparamagnetic behavior phenomenon based on Moessbauer spectroscopy measurements. The kinetic analyses based on the modified Kissinger method yielded four characteristic stages during the thermal evolution of the 22 hours milled state with activation energies of 0.23 kJ/mol, 2.52 kJ/mol, 0.024 kJ/mol, and 1.57 kJ/mol respectively.

  14. Utilization of aluminum to obtaining a duplex type stainless steel using high energy ball milling; Obtencao de um aco inoxidavel de estrutura duplex do sistema FeMnAl processado por moagem de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Pavlak, I.E.; Cintho, O.M., E-mail: eng.igorpavlak@yahoo.com.b [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil); Capocchi, J.D.T. [Universidade de Sao Paulo (USP), SP (Brazil)

    2010-07-01

    The obtaining of stainless steel using aluminum in its composition - FeMnAl system, has been researches subject since the sixties, by good mechanical properties and resistance to oxidation presented, when compared with conventional FeNiCr stainless steel system. In another point, the aluminum and manganese are low cost then traditional elements. This work, metallic powders of iron, manganese and pure aluminum, were processed in a Spex type high-energy ball mill in nitrogen atmosphere. The milling products were compressed into pastille form and sintered under inert atmosphere. The final products were characterized by optical and electronic microscopy and microhardness test. The metallographic analysis shows a typical austenite and ferrite duplex type microstructure. The presence of these phases was confirmed according X ray diffraction analysis. (author)

  15. A Novel Hybrid Error Criterion-Based Active Control Method for on-Line Milling Vibration Suppression with Piezoelectric Actuators and Sensors

    Directory of Open Access Journals (Sweden)

    Xingwu Zhang

    2016-01-01

    Full Text Available Milling vibration is one of the most serious factors affecting machining quality and precision. In this paper a novel hybrid error criterion-based frequency-domain LMS active control method is constructed and used for vibration suppression of milling processes by piezoelectric actuators and sensors, in which only one Fast Fourier Transform (FFT is used and no Inverse Fast Fourier Transform (IFFT is involved. The correction formulas are derived by a steepest descent procedure and the control parameters are analyzed and optimized. Then, a novel hybrid error criterion is constructed to improve the adaptability, reliability and anti-interference ability of the constructed control algorithm. Finally, based on piezoelectric actuators and acceleration sensors, a simulation of a spindle and a milling process experiment are presented to verify the proposed method. Besides, a protection program is added in the control flow to enhance the reliability of the control method in applications. The simulation and experiment results indicate that the proposed method is an effective and reliable way for on-line vibration suppression, and the machining quality can be obviously improved.

  16. An explorative analysis of process and formulation variables affecting comilling in a vibrational mill: The case of praziquantel.

    Science.gov (United States)

    Beatrice Perissutti; Passerini, Nadia; Trastullo, Ramona; Keiser, Jennifer; Zanolla, Debora; Zingone, Guglielmo; Voinovich, Dario; Albertini, Beatrice

    2017-11-30

    Praziquantel, a BCS II class anthelmintic drug used for the treatment of schistosome infections, was coground in a vibrational mill with different polymers (linear and crosslinked povidone, copovidone and sodium starch glycolate). An explorative analysis of formulation variables (drug-polymer wt ratio and polymer type) and process parameters (type of grinding media, grinding time and frequency) was carried out with the help of an experimental screening design. The influence of the above mentioned factors on three PZQ characteristics (residual crystallinity, water solubility enhancement and drug recovery) was studied. The variation of carrier amount proved to be by far the most important variable affecting all the experimental responses. A lower impact and, in some cases, rather null effect, had the variation of the process variables. All coground systems were characterized by a high amorphous degree and a solubility significantly higher than the API. A very promising product was obtained by processing at 20Hz for 4h, using 3 spheres of 15mm as grinding media, i.e. a coground having a 50% API content, showing a 4.6-fold greater solubility at 20°C than pure praziquantel. This product maintained the same antischistosomal activity of pure API and was both physically and chemically stable for at least 6 months. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Modelling and Simulation of a New Variable Stiffness Holder for Milling of Flexible Details

    Directory of Open Access Journals (Sweden)

    Kaliński Krzysztof J.

    2017-04-01

    Full Text Available Modern industry expectations in terms of milling operations often demand the milling of the flexible details by using slender ball-end tools. This is a difficult task because of possible vibration occurrence. Due to existence of certain conditions (small depths of cutting, regeneration phenomena, cutting process may become unstable and self-excited chatter vibration may appear. Frequency of the chatter vibration is close to dominant natural frequency of the workpiece or the tool. One of the methods of chatter vibration avoidance is matching the spindle speed to the optimum phase shift between subsequent cutting edges passes (i.e. the Liao-Young condition. However, the set of optimum spindle speeds from the point of view of vibration reduction may be not optimum one from other points of view. For example milling efficiency or machine tool capabilities cannot be assured. This article presents the idea of a workpiece holder with adjustable stiffness and discusses a new variant of its realization. In the holder, milling process is performed at constant spindle speed and feed speed. In order to avoid vibration the holder stiffness is modified. Stiffness changes modify natural frequencies of the workpiece and thus it is possible to modify dynamic properties of the workpiece in such a way that arbitrary chosen, constant spindle speed will be optimum, due to the Liao-Young condition performance. Calculation of the optimum stiffness is performed before milling, based on the workpieces modal identification results and the finite element model simulations.

  18. Effect of ball milling and thermal treatment on exchange bias and magnetocaloric properties of Ni{sub 48}Mn{sub 39.5}Sn{sub 10.5}Al{sub 2} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, P., E-mail: p.czaja@imim.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Kraków (Poland); Przewoźnik, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Department of Solid State Physics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Fitta, M.; Bałanda, M. [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 152 Radzikowskiego Str., 31-342 Krakow (Poland); Chrobak, A. [A. Chelkowski Institute of Physics, University of Silesia, 4 Uniwersytecka Str., Katowice 40-007 (Poland); Kania, B. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Kraków (Poland); Zackiewicz, P. [Institute of Non Ferrous Metals, 5 Sowinskiego Str., Gliwice 44-100 (Poland); Wójcik, A.; Szlezynger, M.; Maziarz, W. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Kraków (Poland)

    2016-03-01

    The combined effect of ball milling and subsequent heat treatment on microstructure, magnetic, magnetocaloric and exchange bias properties of Ni{sub 48}Mn{sub 39.5}Sn{sub 10.5}Al{sub 2} ribbons is reported. The annealing treatment results in the increase of the critical martensitic transformation temperature. The magnetic entropy change ΔS{sub M} of the order of 7.9 and −2.3 J kg K{sup −1} for the annealed 50–32 µm powder fraction is determined. This is less than in the as melt spun ribbon but appears at a considerably higher temperature. At the same time EB is decreased due to annealing treatment. This decrease is attributed to the strengthened ferromagnetic exchange coupling due heat induced stress and structural relaxation. - Highlights: • Milling and annealing of Ni–Mn–Sn–Al ribbons increases the MT temperature. • ΔS{sub M} equal to 7.9 and −2.3 J kg K{sup −1} for the annealed 50–32 µm powder fraction. • Exchange Bias decreases due to annealing treatment. • Milling and annealing are useful for tuning of properties of Ni–Mn–Sn–Al alloys.

  19. Binary modelling the milling of UG2 ore using a matrix approach

    Directory of Open Access Journals (Sweden)

    Méschac-Bill Kime

    2017-04-01

    Full Text Available The study reports a binary matrix modelling and simulation studies to improve the performance of the secondary grinding circuit of UG2 ores. The model developed was intended to help searching for optimal operating conditions of the secondary milling circuit so that the platinum group element (PGE recovery is increased while reducing Cr2O3 entrainment in the subsequent flotation stage. A series of laboratory batch-scale tests was carried out in order to estimate the milling kinetics parameters of the chromite and non-chromite components. Finally, two alternatives circuit configurations for a better performance were evaluated using simulations. The optimal design consisted of a conventional ball mill in closed circuit with a hydrocyclone to separate the milling product into lights (non-chromite-rich and heavies (chromite-rich fractions followed by a vibrating screen to de-slime the cyclone underflow before it is returned to the mill for further grinding.

  20. Record critical current densities in IG processed bulk YBa{sub 2}Cu{sub 3}O{sub y} fabricated using ball-milled Y{sub 2}Ba{sub 1}Cu{sub 1}O{sub 5} phase

    Energy Technology Data Exchange (ETDEWEB)

    Muralidhar, Miryala; Kenta, Nakazato; Murakami, Masato [Department of Materials Science and Engineering, Superconducting Materials Laboratory, Shibaura Institute of Technology, Tokyo (Japan); Zeng, XianLin; Koblischka, Michael R. [Institute of Experimental Physics, Saarland University, Saarbruecken (Germany); Diko, Pavel [Institute of Experimental Physics, Material Physics Laboratory, Slovak Academy of Sciences, Kosice (Slovakia)

    2016-02-15

    The infiltration-growth (IG) technique enables the uniform and controllable Y{sub 2}BaCuO{sub 5} (Y211) secondary phase particles formation within the YBa{sub 2}Cu{sub 3}O{sub y} (Y123) matrix. Recent results clarified that the flux pinning performance of the Y123 material was dramatically improved by optimizing the processing conditions during the IG process. In this paper, we adapted the IG technique and produced several samples with addition of nanometer-sized Y211 secondary phase particles, which were produced by a ball milling technique. We found that the performance of the IG processed Y123 material dramatically improved in the low field region for a ball milling time of 12 h as compared to the samples without a ball milling step. Magnetization measurements showed a sharp superconducting transition with an onset T{sub c} at around 92 K. The critical current density (J{sub c}) at 77 K and zero field was determined to be 224 022 Acm{sup -2}, which is higher than the not ball-milled sample. Furthermore, microstructural observations exhibited a uniform microstructure with homogenous distribution of nanosized Y-211 inclusions within the Y-123 matrix. The improved performance of the Y-123 material can be understood in terms of fine distribution of the secondary phases. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Investigation of the milling-induced thermal behavior of crystalline and amorphous griseofulvin.

    Science.gov (United States)

    Trasi, Niraj S; Boerrigter, Stephan X M; Byrn, Stephen Robert

    2010-07-01

    To gain a better understanding of the physical state and the unusual thermal behavior of milled griseofulvin. Griseofulvin crystals and amorphous melt quench samples were milled in a vibrating ball mill for different times and then analyzed using differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Modulated DSC (mDSC) and annealing studies were done for the milled amorphous samples to further probe the effects of milling. Milling of griseofulvin crystals results in decrease in crystallinity and amorphization of the compound. A double peak is seen for crystallization in the DSC, which is also seen for the milled melt quench sample. Both enthalpy and temperature of crystallization decrease for the milled melt quenched sample. Tg is visible under the first peak with the mDSC, and annealing shows that increasing milling time results in faster crystallization upon storage. Milling of griseofulvin results in the formation of an amorphous form and not a mesophase. It increases the amount of surface created and the overall energy of the amorphous griseofulvin, which leads to a decreased temperature of crystallization. The two exotherms in the DSC are due to some particles having nuclei on the surface.

  2. Structural and magnetic properties of Fe{sub 60}Al{sub 40} alloys prepared by means of a magnetic mill

    Energy Technology Data Exchange (ETDEWEB)

    Bernal-Correa, R. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Rosales-Rivera, A., E-mail: arosalesr@unal.edu.c [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Pineda-Gomez, P. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Universidad de Caldas, Manizales (Colombia); Salazar, N.A. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia)

    2010-04-16

    A study on synthesis, structural and magnetic characterization of Fe{sub 60}Al{sub 40} (at.%) alloys prepared by means of mechanical alloying process is presented. The mechanical alloying was performed using a milling device with magnetically controlled ball movement (Uni-Ball-Mill 5 equipment) at several milling times. The characterization was carried out via X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The effects of milling time on the structural state, morphological evolution and magnetic behaviour of the Fe{sub 60}Al{sub 40} (at.%) alloys are discussed. Besides, in this current study we emphasize the result that indicating a ferro-para-ferromagnetic transition from a correlation between X-ray diffraction and magnetization data.

  3. Ball lightning.

    OpenAIRE

    Stenhoff, Mark

    1988-01-01

    Ball lightning is alleged by some to be a rare atmospheric phenomenon usually associated with thunderstorms, while others hold that it does not exist. This controversy has continued for centuries. This study comprises a critical evaluation of evidence for the existence of ball lightning. An historical review of the controversy is first presented, giving a chronological account of developments in ball lightning theories and of important observations alleged to be of the phenomenon. Other pheno...

  4. Non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} on dehydrogenation high-energy ball milled MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Hou, Xiaojiang; Hu, Rui; Kou, Hongchao; Li, Jinshan

    2016-11-01

    MgH{sub 2}-M (M = TiF{sub 3} or Nb{sub 2}O{sub 5} or both of them) composites prepared by high-energy ball milling are used in this work to illustrate the dehydrogenation behavior of MgH{sub 2} with the addition of catalysts. The phase compositions, microstructures, particle morphologies and distributions of MgH{sub 2} with catalysts have been evaluated. The non-isothermal synergetic catalytic-dehydrogenation effect of TiF{sub 3} and Nb{sub 2}O{sub 5} evaluated by differential scanning calorimetry gives the evidences that the addition of catalysts is an effective strategy to destabilize MgH{sub 2} and reduce hydrogen desorption temperatures and activation energies. Depending on additives, the desorption peak temperatures of catalyzed MgH{sub 2} reduce from 417 °C to 341 °C for TiF{sub 3} and from 417 °C to 336 °C for Nb{sub 2}O{sub 5}, respectively. The desorption peak temperature reaches as low as 310 °C for MgH{sub 2} catalyzed by TiF{sub 3} coupling with Nb{sub 2}O{sub 5}. The non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} is mainly attributed to electronic exchange reactions with hydrogen molecules, which improve the recombination of hydrogen atoms during dehydrogenation process of MgH{sub 2}. - Highlights: • Catalytic surface for MgH{sub 2} is achieved by high-energy ball milling. • Non-isothermal dehydrogenation behavior of MgH{sub 2} with TiF{sub 3} and/or Nb{sub 2}O{sub 5} is illustrated. • Dehydrogenation activation energies of synergetic catalyzed MgH{sub 2} are obtained. • Synergetic catalytic-dehydrogenation mechanism of TiF{sub 3} and Nb{sub 2}O{sub 5} is proposed.

  5. Fixation system with high-efficiency vibration damping for titanium milling. Chip removal; Werkzeugspannsystem mit hoher Vibrationsdaempfung zur Titanbearbeitung. Schwerzerspanung

    Energy Technology Data Exchange (ETDEWEB)

    Broennimann, Martin [Rego-Fix AG, Tenniken (Switzerland)

    2009-06-08

    Difficult materials like titanium are common in the aerospace industry. With a high-efficiency fixation system and an optimized milling strategy, propulsion system producer MTU was able to enhance productivity in titanium blisk production. The working time was reduced by 42 % and the tool cost by 76 %. (orig.)

  6. Characterization of nanostructured alpha-Fe2O3-SnO2 solid solutions prepared by high energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, R.; Mørup, Steen

    1998-01-01

    Solid solutions of SnO2 in alpha-Fe2O3 with SnO2 contents up to 20+-4 mol% have been prepared by mechanical alloying of alpha-Fe2O3 and SnO2 powder blends. X-ray diffraction and Mossbauer spectroscopy investigations show that the mechanical milling results in alloying on an atomic scale...... and that true solid solution formation occurs. We suggest that the high defect concentration and the chemical enthalpy of Fe3+ -O2- -Sn4+ interfaces between nanostructured alpha-Fe2O3 and SnO2 regions may serve as a driving force for the formation of a solid solution in the immiscible ceramic system....

  7. Microstructure and gas sensitive properties of alpha-Fe2O3-MO2 (M: Sn and Ti) materials prepared by ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, R.; Mørup, Steen

    1998-01-01

    Metastable alpha-Fe2O3-MO2 (M: Sn and Ti) solid solutions can be synthesized by mechanical alloying. The alloy formation, microstructure, and gas sensitive properties of mechanically milled alpha-Fe2O3-SnO2 materials are discussed. Tin ions in alpha-Fe2O3 are found to occupy the empty octahedral...... holes in the alpha-Fe2O3 lattice. This interstitial model can also describe the structure of alpha-Fe2O3-TiO2 solid solutions. Finally, a correlation of gas sensitive properties with microstructure of alpha-Fe2O3-SnO2 materials is presented....

  8. Science of Ball Lightning (Fire Ball)

    Science.gov (United States)

    Ohtsuki, Yoshi-Hiko

    1989-08-01

    The Table of Contents for the full book PDF is as follows: * Organizing Committee * Preface * Ball Lightning -- The Continuing Challenge * Hungarian Ball Lightning Observations in 1987 * Nature of Ball Lightning in Japan * Phenomenological and Psychological Analysis of 150 Austrian Ball Lightning Reports * Physical Problems and Physical Properties of Ball Lightning * Statistical Analysis of the Ball Lightning Properties * A Fluid-Dynamical Model for Ball Lightning and Bead Lightning * The Lifetime of Hill's Vortex * Electrical and Radiative Properties of Ball Lightning * The Candle Flame as a Model of Ball Lightning * A Model for Ball Lightning * The High-Temperature Physico-Chemical Processes in the Lightning Storm Atmosphere (A Physico-Chemical Model of Ball Lightning) * New Approach to Ball Lightning * A Calculation of Electric Field of Ball Lightning * The Physical Explanation to the UFO over Xinjiang, Northern West China * Electric Reconnection, Critical Ionization Velocity, Ponderomotive Force, and Their Applications to Triggered and Ball Lightning * The PLASMAK™ Configuration and Ball Lightning * Experimental Research on Ball Lightning * Performance of High-Voltage Test Facility Designed for Investigation of Ball Lightning * List of Participants

  9. Effects of surfactant addition and high-speed ball milling on magnetic powders based on Pr-Fe-B obtained by HDDR; Efeitos da adicao de surfactante e moagem de alta velocidade em pos magneticos a base de Pr-Fe-B obtidos via HDDR

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Patricia Brissi

    2011-07-01

    This work verified the effect caused by adding the surfactant in the high speed/energy milling in order to obtain Pr{sub 12}Fe{sub 65.9}Co{sub 16}B{sub 6}Nb{sub 0.1} magnetic nano powders. The first part of this work involved the magnetic powder obtainment through the process of hydrogenation, disproportionation, desorption and recombination (HDDR). The pressure of H2 during the hydrogenation and disproportion steps was 930 mbar and the temperature of desorption and recombination was 840 deg C. Initially, the HDDR powders were subjected a high speed milling process at 900 rpm, with quantity variations of the milling medium (cyclohexane) and without the addition of oleic acid. Then, the HDDR powders were subjected to the milling process with the addition of oleic acid and with milling time variations. After the milling process, heat treatments of the powder were carried out at 700 deg C or 800 deg C for 30 minutes in order to obtain the crystallization of the powder. By performing the procedures, it was verified that the milling efficiency improved with the addition of 6.6 ml of cyclohexane as the milling medium and with the addition of oleic acid. It was determined that for the surfactant additions of 0.02 ml to 0.05 ml, with a milling time of up to 360 minutes, powder agglomeration does not occur in the milling pot and the milling efficiency is higher than 90%. The second stage of this work involved the magnetic powder's characterization obtained by using vibrating sample magnetometer, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Through the characterizations it was found that the powder's magnetic properties improved when the addition of oleic acid in a high-speed /energy milling occurred. It was also verified that the {alpha}-Fe phase, present in the powder, shows a crystallite size decrease (from 35 nm to {approx} 10 nm) when the time milling variation occurred; meanwhile, the crystallinity degree was lower in

  10. A dynamic styrofoam-ball model for simulating molecular motion

    Science.gov (United States)

    Mak, Se-yuen; Cheung, Derek

    2001-01-01

    In this paper we introduce a simple styrofoam-ball model that can be used for simulating molecular motion in all three states. As the foam balls are driven by a vibrator that is in turn driven by a signal generator, the frequency and the amplitude of vibration can be adjusted independently. Thus, the model is appropriate for simulating molecular motion in the liquid state, which is a combination of vibration and meandering motion.

  11. Online SAG Mill Pluse Measurement and Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Raj Rajamani; Jose Delgadillo; Vishal Duriseti

    2007-06-30

    The grinding efficiency of semi autogenous milling or ball milling depends on the tumbling motion of the total charge within the mill. Utilization of this tumbling motion for efficient breakage of particles depends on the conditions inside the mill. However, any kind of monitoring device to measure the conditions inside the mill shell during operation is virtually impossible due to the severe environment presented by the tumbling charge. An instrumented grinding ball, which is capable of surviving a few hours and transmitting the impacts it experiences, is proposed here. The spectrum of impacts collected over 100 revolutions of the mills presents the signature of the grinding environment inside mill. This signature could be effectively used to optimize the milling performance by investigating this signature's relation to mill product size, mill throughput, make-up ball size, mill speed, liner profile and ball addition rates. At the same time, it can also be used to design balls and liner systems that can survive longer in the mill. The technological advances made in electronics and communication makes this leap in instrumentation certainly viable. Hence, the instrumented grinding ball offers the ability to qualitatively observe and optimize the milling environment. An instrumented load cell package that can measure the force of impacts inside the grinding chamber of a mill is developed here. The signal from the instrumented load cell package is interpreted in terms of a histogram termed as an impact spectrum which is a plot of the number of impacts at a specific energy level against the energy. It reflects on the average force regime of the mill. The instrumented load cell package was calibrated against the ultra fast load cell which has been unanimously accepted as a standard to measure single breakage events. The load cell package was successfully used to produce impact spectra in an 8.5 inch lab scale mill. The mill speed and the ball size were varied to

  12. Optimizing the performance of Li4Ti5O12 anode synthesized from TiO2 xerogel and LiOH with hydrothermal-ball mill method by using acetylene black

    Science.gov (United States)

    Priyono, Bambang; Murti, P. B.; Syahrial, Anne Z.; Subhan, A.

    2017-03-01

    Optimizing the Li-ion Batteries performance using Li4Ti5O12 (LTO) as anode material by addition of using Acetylene Black was studied in this research. The LTO was successfully synthesized using sol-gel method to form TiO2 xerogel continued by calcination, hydrothermal, ball milling and sintering process. XRD (X-Ray Diffraction), scanning electron microscopy-Energy Dispersive Spectroscopy (SEM-EDS) and Brunauer-Emmett-Teller (BET) was performed to identify the characteristic of Li4Ti5O12 powder likes phase, morphology, chemical composition and surface area. Spinel Li4Ti5O12 and rutile TiO2 were detected in XRD patterns. The morphology of Li4Ti5O12 shows presence of agglomerates structure. The surface area of Li4Ti5O12 powder is 6.404 m2/g. Electrode sheet then be prepared with LTO and mixed with PVDF binder (5 wt%) and AB 5 wt% (LTO-1), 10 wt% PVDF binder and 10wt% AB (LTO-2), 15 wt% PVDF binder and 15 wt% AB (LTO-3) of total weight solid content. Half-cell coin battery was made with lithium counter electrode. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and Charge-discharge (CD) test were performed to examine the performance of Li-ion Batteries. The best result was obtained in LTO-2, due to lowest resistance (27 ohm) and highest initial capacity (146.82 mAh/g). The increasing of AB content affects the rate capability of battery. It can be seen by CD test, where the LTO HT2-AC 1.5 has better rate capability then LTO-2 and LTO-1. LTO-3 has 24% of initial capacity at 10C, when LTO-2 has 21% of initial capacity at 10C, and LTO-1 has no capacity at 10C. It is proved that increasing AB content could lead to rate-capability and cycling performance improvement which reached at the optimum value in the LTO-2.

  13. C, N co-doped TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite coatings prepared from TiC{sub 0.7}N{sub 0.3} powder using ball milling followed by oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Liang, E-mail: haoliang@tust.edu.cn [Tianjin Key Lab of Integrated Design and On-line Monitoring for Light Industry & Food Machinery and Equipment, Tianjin (China); College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Wang, Zhenwei, E-mail: 1004329228@qq.com [School of Naval Architecture and Ocean Engineering, Harbin Institute of Technology, Weihai, No. 2, Wenhua West Road, Weihai 264209 (China); Zheng, Yaoqing, E-mail: 13612177268@163.com [College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Li, Qianqian, E-mail: 1482471595@qq.com [College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Guan, Sujun, E-mail: sujunguan1221@gmail.com [College of Mechanical Engineering & Graduate School, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Zhao, Qian, E-mail: zhaoqian@tust.edu.cn [Tianjin Key Lab of Integrated Design and On-line Monitoring for Light Industry & Food Machinery and Equipment, Tianjin (China); College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Cheng, Lijun, E-mail: chenglijun@tust.edu.cn [Tianjin Key Lab of Integrated Design and On-line Monitoring for Light Industry & Food Machinery and Equipment, Tianjin (China); College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Lu, Yun, E-mail: luyun@faculty.chiba-u.jp [College of Mechanical Engineering & Graduate School, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Liu, Jizi, E-mail: jzliu@njust.edu.cn [Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, No. 200, Xiaolingwei Street, Nanjing 210094 (China)

    2017-01-01

    Highlights: • TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} coatings were prepared by ball milling followed by oxidation. • In situ co-doping of C and N with simultaneous TiO{sub 2} formation was observed. • Improved photocatalytic activity under UV/visible light was noticed. • Synergism in co-doping and heterojunction formation promoted carrier separation. - Abstract: Ball milling followed by heat oxidation was used to prepared C, N co-doped TiO{sub 2} coatings on the surfaces of Al{sub 2}O{sub 3} balls from TiC{sub 0.7}N{sub 0.3} powder. The as-prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrophotometer (UV–vis). The results show that continuous TiC{sub 0.7}N{sub 0.3} coatings were formed after ball milling. C, N co-doped TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite coatings were prepared after the direct oxidization of TiC{sub 0.7}N{sub 0.3} coatings in the atmosphere. However, TiO{sub 2} was hardly formed in the surface layer of TiC{sub 0.7}N{sub 0.3} coatings within a depth less than 10 nm during the heat oxidation of TiC{sub 0.7}N{sub 0.3} coatings in carbon powder. Meanwhile, the photocatalytic activity evaluation of these coatings was conducted under the irradiation of UV and visible light. All the coatings showed photocatalytic activity in the degradation of MB no matter under the irradiation of UV or visible light. The C, N co-doped TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite coatings showed the most excellent performance. The enhancement under visible light irradiation should attribute to the co-doping of carbon and nitrogen, which enhances the absorption of visible light. The improvement of photocatalytic activity under UV irradiation should attribute to the synergistic effect of C, N co-doping, the formation of rutile-anatase mixed phases and the TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite microstructure.

  14. Influence of the charge properties on the milling tools wear during intensive milling in liquid environment

    Directory of Open Access Journals (Sweden)

    Števulová Nadežda

    2002-06-01

    Full Text Available Grinding belongs to the basic technological operations in the treatment and processing of minerals. The method of the intensive grinding in a liquid environment has become attractive for the preparation of technologically advanced materials of the high fineness. Its choice was motivated by the intensification of dispersion and by the protection of ground powder against oxidation. The result of energy and material interactions among the grinding media and grinding environment is the wear of the grinding media and contamination of the ground material. The hardness of the particles has an important influence on the rate of wear. Particles with hardness lower than that of the surface of milling tools cause much less wear than harder particles. The wear rate becomes much more sensitive to the ratio of the abrasive hardness Ha to the surface hardness Hs when Ha/Hs <¡­1.The paper deals with the influence of four minerals with various microhardness (corundum, quartz, silicon and magnesite on the steel milling tools wear during intensive milling.. Experiments were performed in a vibration mill in methanol under same conditions. The grinding time was changed in a geometric sequence from 0,125 to 4 hours. The newly created surface area providesa basic information on grinding. The specific surface area was determined by the standard Brunauer-Emmett-Teller (BET method using the appratus Gemini 2360 (Sylab, Austria. The concentration of iron was determined by AAS (SpectrAA-30, Varian, Australia. It was confirmed that the rate of ball wear depends on the hardness of feed materials. It was found that the relation between the contamination of the ground powders by wear and the specific surface area increment is linear and the slope depends on the microhardness of the ground material.

  15. Effect of milling time on the formation of carbon nanotube by ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 38; Issue 4 ... In this method, graphite powders in the elemental form were firstly exposed to milling process in high-energy ball milling and then the milled powders were ... As a result of milling of the graphite, ultra-active disordered carbon structures were obtained.

  16. Vibration Damping Circuit Card Assembly

    Science.gov (United States)

    Hunt, Ronald Allen (Inventor)

    2016-01-01

    A vibration damping circuit card assembly includes a populated circuit card having a mass M. A closed metal container is coupled to a surface of the populated circuit card at approximately a geometric center of the populated circuit card. Tungsten balls fill approximately 90% of the metal container with a collective mass of the tungsten balls being approximately (0.07) M.

  17. An investigation of the corrosive wear of steel balls in grinding of sulphide ores

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2015-06-01

    Full Text Available Ball mills are common grinding equipment in mineral processing industries. Ball wear results from three mechanisms namely impact, abrasion and corrosion. Of these, the corrosion mechanism is the least investigated, due to its chemical-electrochemical nature. Therefore, the aims of this research were to investigate the grinding chemistry influence (slurry pH, solid percentage, water chemistry and gas purging on corrosive wear of steel balls and to determine the contribution of corrosion mechanism to total wear of steel balls. The results indicated that the mass losses of steel balls could be reduced considerably by controlling the pulp chemistry inside the mill. In addition, the results showed that 73.51% of the corrosion products are generated from the oxidation of steel balls. It was also estimated that the corrosion mechanism accounts for 26.68% of the total wear of steel balls.

  18. Having a Ball with Fitness Balls

    Science.gov (United States)

    McNulty, Betty

    2011-01-01

    Fitness programs can be greatly enhanced with the addition of fitness balls. They are a fun, challenging, economical, and safe way to incorporate a cardiovascular, strength, and stretching program for all fitness levels in a physical education setting. The use of these balls has become more popular during the last decade, and their benefits and…

  19. Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Thanh, Tran Dang, E-mail: thanhxraylab@yahoo.com [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Nanto, Dwi [Physics Education, Syarif Hidayatullah States Islamic University, Jakarta 15412 (Indonesia); Tuyen, Ngo Thi Uyen [Department of Natural Science, Nha Trang Pedagogic College, Nguyen Chanh, Nha Trang, Khanh Hoa (Viet Nam); Nan, Wen-Zhe [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Yu, YiKyung [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Tartakovsky, Daniel M., E-mail: dmt@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Yu, S.C., E-mail: scyu@cbnu.ac.kr [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)

    2015-11-15

    In this work, we prepared nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic–paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order. - Highlights: • Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al nanocrystals were prepared by a high energy ball milling method. • A coexistence of the short- and long-range FM order in the nanocrystals. • Cu doping favors establishing a long-range FM order in the nanocrystals. • All the ΔS{sub m}(T, H) data are followed a universal master curve.

  20. The effect of crystal morphology and mill type on milling induced crystal disorder.

    Science.gov (United States)

    Chikhalia, V; Forbes, R T; Storey, R A; Ticehurst, M

    2006-01-01

    Milling is a key process in the preparation of many solid dosage forms. One possible milling induced change is the production of small levels of disorder or amorphous material found predominantly at the surface of a powder, which could lead to significant chemical and physical instability. The influence of crystal habit on this change was investigated using beta-succinic acid, in plate like and needle like morphologies. beta-Succinic acid crystals with these habits were processed in a ball mill and a jet mill. SEM images indicated jet milled material was finer than the ball milled product. Powder X-ray diffraction of the milled powders revealed an amorphous halo at lower angles and peak broadening suggesting disorder though this could not be quantified accurately. In addition, a partial conversion during milling to the alpha form was noted. Quantitation of the alpha form in the milled powders indicated it was present at powders had lower heats of solution compared to the unmilled powers. The contribution of the alpha polymorph to the lower heats of solution was calculated to be insignificant. Therefore, the reduced heat of solution is attributed to a loss in crystallinity. The largest decreases were seen in the plate like morphology. These findings suggest that beta-succinic acid crystals with plate like morphology are more prone to crystallinity loss on milling compared to the needle like morphology. The mill type has also been shown to influence the final crystallinity.

  1. Swiss ball in physiotherapy

    OpenAIRE

    Hlaváčková, Tereza

    2010-01-01

    In the beginning of my Bachelor thesis "The Swiss ball in Physiotherapy" I mention the basic information, the history, the application of this ball in terms of rehabilitation/ physical therapy and I describe the unique characteristics of this tool. I also discuss practical instructions for use, indication and contraindication for the therapeutic use of the Swiss ball. In the second part of my thesis I describe the proper use of the ball in specific areas of medical application. These areas of...

  2. Birth of ball lightning

    Science.gov (United States)

    Lowke, J. J.; Smith, D.; Nelson, K. E.; Crompton, R. W.; Murphy, A. B.

    2012-10-01

    Many observations of ball lightning report a ball of light, about 10 cm in diameter, moving at about walking speed, lasting up to 20 s and frequently existing inside of houses and even aeroplanes. The present paper reports detailed observations of the initiation or birth of ball lightning. In two cases, navigation crew of aircraft saw ball lightning form at the windscreen inside the cockpit of their planes. In the first case, the ball lightning occurred during a thunderstorm, with much lightning activity outside of the plane. In the second case, large "horns" of electrical corona were seen outside of the plane at the surface of the radome, just prior to the formation of the ball lightning. A third case reports ball lightning formed inside of a house, during a thunderstorm, at a closed glass window. It is proposed, based on two-dimensional calculations of electron and ion transport, that ball lightning in these cases is driven and formed by atmospheric ions impinging and collecting on the insulating surface of the glass or Perspex windows. This surface charge can produce electric fields inside of the cockpit or room sufficient to sustain an electric discharge. Charges of opposite sign to those outside of the window accumulate on the inside surface of the glass, leaving a ball of net charge moving inside of the cockpit or room to produce a pulsed discharge on a microsecond time scale.

  3. Characterization of Al{sub 2}O{sub 3}NP-Al{sub 2024} and Ag{sub C}NP-Al{sub 2024} composites prepared by mechanical processing in a high energy ball mill

    Energy Technology Data Exchange (ETDEWEB)

    Carreno-Gallardo, C. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia-Chihuahua, Miguel de Cervantes No. 120, C.P. 31109, Chihuahua (Mexico); Universidad Autonoma Metropolitana, Departamento de Materiales, Av. San Pablo No. 180, Col Reynosa-Tamaulipas, CP 02200, D.F. (Mexico); Estrada-Guel, I. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia-Chihuahua, Miguel de Cervantes No. 120, C.P. 31109, Chihuahua (Mexico); Romero-Romo, M. [Universidad Autonoma Metropolitana, Departamento de Materiales, Av. San Pablo No. 180, Col Reynosa-Tamaulipas, CP 02200, D.F. (Mexico); Cruz-Garcia, R. [Universidad Autonoma de Chihuahua (UACH), Facultad de Ingenieria, Circuito No. 1 Nuevo Campus Universitario, C.P. 31125, Chihuahua (Mexico); Lopez-Melendez, C. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia-Chihuahua, Miguel de Cervantes No. 120, C.P. 31109, Chihuahua (Mexico); Universidad La Salle Chihuahua, Prol. Lomas de Majalca No. 11201, C.P. 31020, Chihuahua (Mexico); Martinez-Sanchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia-Chihuahua, Miguel de Cervantes No. 120, C.P. 31109, Chihuahua (Mexico)

    2012-09-25

    Graphical abstract: Mechanical alloying was used to produce two kinds of metal matrix composites based on 2024 aluminum alloy, the nanocomposites were reinforced with different percentages of Al{sub 2}O{sub 3} and Ag{sub C} nanoparticles. The content of nanoparticles has a role important on the mechanical properties of the nanocomposite. 10 h of milling time are enough to former the Al{sub 2024} nanocomposites. The results obtained by differential scanning calorimeter show the temperatures of intermetallic precipitation, which were identified by X-ray diffraction. The results revealed that mechanical alloying is an excellent route to incorporate and distribute NP into Al{sub 2024}. Highlights: Black-Right-Pointing-Pointer Aluminum-based nanocomposites were synthesized bay milling process. Black-Right-Pointing-Pointer An homogeneous nanoparticles dispersion was reached and mechanical properties were enhanced. Black-Right-Pointing-Pointer Phase transformation during heating was characterized by XRD. - Abstract: Mechanical alloying was used to produce two kinds of metal matrix composites based on 2024 aluminum alloy. The nanocomposites were reinforced with different percentages of Al{sub 2}O{sub 3} and Ag{sub C} nanoparticles. The content of nanoparticles has an important role on the mechanical properties of the nanocomposites. A milling time of 10 h is enough to form the Al{sub 2024} nanocomposites. The thermograms obtained by differential scanning calorimeter show the temperatures of phase precipitation, which were identified by X-ray diffraction. The results revealed that mechanical alloying is an excellent route for the incorporation and distribution of nanoparticles into Al{sub 2024}.

  4. Influence of Milling parameters in the morphology of nanostructured CrC-30wt%NiCr

    Directory of Open Access Journals (Sweden)

    Waleska Campos Guaglianoni

    2017-01-01

    Full Text Available Nanostructured CrC-30wt%NiCr powders were synthesized by high energy ball milling in a planetary ball mill. Two ball-to-powder ratios, four milling times and two milling speeds were used. Morphology, average grain diameter, and phase transformation of the powders were characterized by scanning electron microscopy (SEM, particle size analysis, and X-ray diffraction (XRD. Crystallite size and mean diameter decrease with increase in BPR, milling time and speed. The results show that with the use of a ball-to-powder weight ratio of 1:20, a milling time of 1h and a milling speed of 500 rpm, the average particle size and crystallite size were respectively 5.6µm and 8.3nm.

  5. Great balls of fire

    Science.gov (United States)

    Stenhoff, Mark; reader01; jjherrera

    2014-03-01

    In reply to the physicsworld.com news article “Burning soil fuels ball lightning” (9 January, http://ow.ly/tl8aO) on evidence that a burning core of soil acts as an energy source for ball lightning.

  6. Relación entre factores micro- estructurales e impacto repetido en aleaciones de alto cromo para bolas de molino. // Relationship among factors micro - structural and impact repeated in alloys of high chromium for mill balls.

    Directory of Open Access Journals (Sweden)

    E. Albertin

    2008-01-01

    Full Text Available Las aleaciones de alto cromo son empleadas para la fabricación de bolas de molino en industrias de procesamiento deminerales. Los usuarios y fabricantes requieren lograr mejores resultados técnicos-económicos en sus aplicaciones, por loque necesitan aumentar los conocimientos relacionados con los aspectos estructurales de estos materiales. En este trabajo serealiza una investigación con vistas a establecer relaciones entre la estructura de las aleaciones y su comportamiento ante elimpacto repetido que es un fenómeno característico en estos procesos.Se funden bolas con varias aleaciones hipo eutécticas, eutécticas, e hipereutécticas; se prueban en un equipo que simula elimpacto repetido. Los resultados permiten comprobar los buenos resultados de aleaciones hipo eutécticas con relaciones deCr/C altas y a su vez altos contenidos de Cr y de aleaciones eutécticas para menores relaciones de Cr/C y menorescontenidos de Cr, en ambos casos los carburos eutécticos son de forma simétrica, regulares y no forman redes continuas decarburos asimétricos bordeando los granos, que presentan peores comportamiento en el impacto repetido y que son el casode las hipoeutécticas con bajas relaciones Cr/C y las hipereutécticas donde aparecen también grandes carburos primariosPalabras claves: Alto-cromo, bolas de molino, impacto repetido, desgaste.____________________________________________________________________________Abstract.High Chromium alloys are used to manufacture grinding balls for the Industry of Construction Materials. Customers andusers need to improve their knowledge about the relationships between microstructure and the parts damage in these alloysto obtain better technical-economics results. In this paper the results of a research to obtain different microstructures ofeutectics, hipoeutectics and hipereutectics alloys are presented, searching for the lesser damage in these alloys. These alloysare tested in a repeated impact testing

  7. Happy Balls, Unhappy Balls, and Newton's Cradle

    Science.gov (United States)

    Kagan, David

    2010-01-01

    The intricacies of Newton's Cradle are well covered in the literature going as far back as the time of Newton! These discussions generally center on the highly elastic collisions of metal spheres. Thanks to the invention of happy and unhappy balls, you can build and study the interaction of less elastic systems (see Fig. 1).

  8. Compact Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D., E-mail: bazeia@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Losano, L.; Marques, M.A. [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Menezes, R. [Departamento de Ciências Exatas, Universidade Federal da Paraíba, 58297-000 Rio Tinto, PB (Brazil); Departamento de Física, Universidade Federal de Campina Grande, 58109-970 Campina Grande, PB (Brazil); Rocha, R. da [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, 09210-580 Santo André (Brazil)

    2016-07-10

    In this work we deal with non-topological solutions of the Q-ball type in two space–time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

  9. Preparation and microwave absorbing properties in the X-band of natural ferrites from iron sands by high energy milling

    Science.gov (United States)

    Mashuri, X.; Lestari, W.; Triwikantoro, X.; Darminto, X.

    2018-01-01

    Bulk natural ferrites based in iron sands were synthesized at room temperature by high energy ball milling. The reduced particle sizes of the ferrites were milled at 100 rpm at selected time intervals of 0, 2, 4, and 6 h. The as-milled products were then characterized by x-ray diffraction (XRD), a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA). The results showed that the magnetite phase contents, their mean size and the saturated magnetization of the natural ferrites were about 95 nm and 36–.50 emu g‑1 without a new phase. The microwave absorbing characteristics were investigated by measuring the absorption of electromagnetic waves in the frequency range 7–12 GHz. The maximum reflection loss (RL m) and matching frequency (f m) for the best process of milling (100 rpm, 6 h) of natural ferrites were RL m1  =  ‑7.28 dB in f m1  =  7.50 GHz (▵f  =  1.50 GHz) and RL m2  =  ‑4.31 dB in f m2  =10.28 GHz (▵f  =  2.57 GHz). These results suggest that synthesized natural ferrites can be employed as effective microwave absorbers in various devices.

  10. Evolution Study of Crystal Parameter for Iron Powder Subjected to Mechanical Milling

    Directory of Open Access Journals (Sweden)

    Ioan TĂUT

    2003-03-01

    Full Text Available In a planetary mill with balls of high energy, the experiences of milling on different time interval of iron powder were done. The iron powder with 99.9% purity was introduced in four vials, having every one on average mass of 1.750 kg, varying the number and diameter of balls. It was noticed, there is a tendency to increase accentuated the crystallographic parameter in the interval of 7.5-9 mm ball radius, it is admitted the same interval to be more efficiently on milling from point of view of evolution of crystal parameter from experimental data.

  11. Formation of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Silberg, P.A. (2833 Lawton Drive, Amarillo, Texas (USA))

    A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which under certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma.

  12. Influence of the milling parameters on the nucleophilic substitution reaction of activated β-cyclodextrins

    Directory of Open Access Journals (Sweden)

    László Jicsinszky

    2017-09-01

    Full Text Available The present work focuses on the mechanochemical preparation of industrially important β-cyclodextrin (CD derivatives. Activated CDs have been reacted with nitrogen and sulfur nucleophiles using a planetary mill equipped with stainless steel, zirconia and glass milling tools of different sizes. It is shown that the milling frequency and the number as well as the size of the milling balls have an effect on the nucleophilic reaction.

  13. Room temperature ferromagnetism and CH{sub 4} gas sensing of titanium oxynitride induced by milling and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Bolokang, Amogelang S., E-mail: Sylvester.Bolokang@transnet.net [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); Transnet Engineering, Product Development, Private Bag X 528, Kilnerpark, 0127 (South Africa); Tshabalala, Zamaswazi P. [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); Malgas, Gerald F. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville, 7535 (South Africa); Kortidis, Ioannis [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); West Virginia University, Department of Mechanical & Aerospace Engineering, Evansdale Campus, Morgantown, WV, 26506 (United States); Swart, Hendrik C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA9300 (South Africa); Motaung, David E., E-mail: dmotaung@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa)

    2017-06-01

    We report on the room temperature ferromagnetism and CH{sub 4} gas sensing of titanium oxynitride prepared by milling and annealing at 1100 °C in a nitrogen gas environment. Structural analyses revealed a metastable orthorhombic TiO{sub 2} phase after milling for 120 h. The 120 h milled TiO{sub 2} particles and subsequently annealed in nitrogen gas at 1100 °C showed the formation of titanium oxynitride (TiO{sub x}N{sub y}) with a tetragonal crystal structure. An FCC metastable TiO{sub x}N{sub y} phase was also observed with a lattice parameter a = 4.235 Å. The vibrating sample magnetometer and electron paramagnetic analyses showed that the milled and TiO{sub x}N{sub y} samples possess room temperature ferromagnetism. Gas sensing measurements were carried out toward CH{sub 4} and H{sub 2} gases. The TiO{sub x}N{sub y} nanostructures demonstrated higher sensing response and selectivity to CH{sub 4} gas at room temperature. The enhanced response of 1010 and sensitivity of 50.12 ppm{sup -1} at a concentration of 20 ppm CH{sub 4} are associated with higher surface area, pore diameter and surface defects such as oxygen vacancies and Ti{sup 3+}, as evidenced from the Brunauer–Emmet–Teller, photoluminescence, electron paramagnetic resonance and x-ray photoelectron analyses. - Highlights: • Ball milled of TiO{sub 2} structure revealed metastable orthorhombic phase. • Upon nitridation tetragonal and FCC TiO{sub x}N{sub y} crystal structures were induced. • The magnetic properties of TiO{sub 2} nanoparticles was transformed by milling. • TiO{sub x}N{sub y} sensing response for CH{sub 4} gas at room temperature was high.

  14. Effect of wet grinding on structural properties of ball clay

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, A., E-mail: anuradha.purohit34@gmail.com; Chander, S.; Dhaka, M. S. [Department of Physics, Mohanlal Sukhadia University, Udaipur-313001 (India); Hameed, A.; Singh, P. [Department of Ceramic Engineering, Govt. College of Engineering and Technology, Bikaner-334004 (India); Nehra, S. P. [Centre of Excellence for Energy and Environmental Studies, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat-131039 (India)

    2015-05-15

    In this paper, the effect of wet grinding on structural properties of ball clay is undertaken. The wet grinding treatment was performed employing ball and vibro mills for different time spells of 2, 4, 8 and 16 hours. The structural properties were carried out using X-ray diffraction (XRD). The structure of ground samples is found to be simple cubic. The crystallographic parameters are calculated and slight change in lattice constant, inter planner spacing and particle size is observed with grinding treatment. The results are in agreement with the available literature.

  15. Ball lightning burn.

    Science.gov (United States)

    Selvaggi, Gennaro; Monstrey, Stan; von Heimburg, Dennis; Hamdi, Mustapha; Van Landuyt, Koen; Blondeel, Phillip

    2003-05-01

    Ball lightning is a rare physical phenomenon, which is not yet completely explained. It is similar to lightning but with different, peculiar characteristics. It can be considered a mix of fire and electricity, concentrated in a fireball with a diameter of 20-cm that most commonly appears suddenly, even in indoor conditions, during a thunderstorm. It moves quickly for several meters, can change direction, and ultimately disappears. During a great storm, a 28-year-old man and his 5-year-old daughter sustained burn wounds after ball lightning came from the outdoors through a chimney. These two patients demonstrated signs of fire and electrical injuries. The father, who lost consciousness, sustained superficial second-degree burn wounds bilaterally on the zygomatic area and deep second-degree burn wounds on his right hand (total body surface area, 4%). His daughter demonstrated superficial second-degree burn wounds on the left part of the face and deep second-degree and third-degree burn wounds (total body surface area, 30%) on the left neck, both upper arms, and the back. In this article, the authors report the first two cases of burn injuries resulting from ball lightning contact indoors. The literature on this rare phenomenon is reviewed to elucidate the nature of ball lightning. Emphasis is placed on the nature of injuries after ball lightning contact, the therapy used, and the long-term complications.

  16. The bowling balls

    CERN Document Server

    CERN Bulletin

    2010-01-01

    10 November 1972: CERN’s Bent Stumpe places an order for 12 bowling balls for a total cost of 95 US dollars. Although not evident at first sight, he is buying the heart of some of the first tracking devices to be used in the SPS control room. Today, Bent Stumpe’s device would be called a desktop mouse…   The first order for 4 bowling balls later changed to 12 balls. The bowling balls became the heart of Bent Stumpe's mouse. Almost 40 years ago, the web, Wikipedia and Google did not exist and it was much more difficult to know whether other people in other parts of the world or even in the same laboratory were facing the same problems or developing the same tools. At that time, Bent Stumpe was an electronics engineer, newly recruited to work on developments for the SPS Central Control room. One of the things his supervisor asked him to build as soon as possible was a device to control a pointer on a screen, also called a tracker ball. The heart of the device was the...

  17. On the magnetic properties of pseudo-Laves phases RE{sub 1-y}Y{sub y}Ni{sub 4-x}Al{sub x}Mg with RE = La, Ce and Gd prepared by both melting and ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, S.; Chevalier, B. [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, 33600 Pessac (France); Paul-Boncour, V. [ICMPE-CMTR, CNRS-UPEC, UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais (France); Bobet, J.-L., E-mail: bobet@icmcb-bordeaux.cnrs.fr [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, 33600 Pessac (France)

    2012-06-05

    Highlights: Black-Right-Pointing-Pointer LaNi{sub 4}Mg did not exhibit any magnetic ordering but a paramagnetic behaviour. Black-Right-Pointing-Pointer All the compounds with Gd order ferromagnetically at a temperature ranging from 77 to 15 K. Black-Right-Pointing-Pointer Dilution of Gd atom by Y leads to a decrease of the Curie temperature below a critical number of Gd atoms. - Abstract: Magnetic properties of RE{sub 1-y}Y{sub y}Ni{sub 4-x}Al{sub x}Mg (RE = La, Ce and Gd) are reported. LaNi{sub 4}Mg displays a weak magnetization indicating that Ni is non magnetic as often observed in RENi{sub 2} compounds. The magnetization of CeNi{sub 4}Mg compounds shows a Curie Weiss behaviour with an effective paramagnetic moment {mu}{sub eff} = 2.2 {mu}{sub B}. The magnetization of Gd compounds is dominated by the contribution of Gd moment with a paramagnetic effective moment close to 7.7 {mu}{sub B}/Gd for all studied compounds. The Curie temperature, which is 75 K for GdNi{sub 2}, decreases almost linearly with the number of Gd neighbours when more than half Gd is replaced by Y. The decrease of crystallinity of GdNi{sub 4}Mg, which is monitored by ball milling and heat treatment, strongly influences the magnetic properties and a relationship between the transition temperature and the crystallites size is reported.

  18. Ball game popularity

    OpenAIRE

    Gregorič, Vanja

    2011-01-01

    In the diploma thesis I present ball games and how they are popular among children of 4th and 5th form of primary school. Sport activities play an important role when growing up and it is up to adults to provide children a certain amount of exercise in the pre-school period and during their schooling. It is important that one considers child's age and that the activities are represented through playing. Ball games are included in the curriculum in one of the sets in the first three years. In ...

  19. mill grinding plates

    African Journals Online (AJOL)

    User

    ABSTRACT. Maize was milled either 'wet' or ''dry'' using locally-manufactured milling plates. Samples of milled maize were taken and analyzed for elemental iron (Fe). Results show that iron particles from milling plates contaminates the milled maize and that the level of contamination increases with the quantity of milled ...

  20. Laboratory demonstration of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, Anton I; Stepanov, Sergei I; Shabanov, Gennadii D [B.P. Konstantinov St. Petersburg Institute of Nuclear Physics, Russian Academy of Sciences, Gatchina, Leningrad region, Rusian Federation (Russian Federation)

    2004-01-31

    A common laboratory facility for creating glowing flying plasmoids akin to a natural ball lightning, allowing a number of experiments to be performed to investigate the main properties of ball lightning, is described. (methodological notes)

  1. The Influence of Milling on the Dissolution Performance of Simvastatin

    Directory of Open Access Journals (Sweden)

    Thomas Rades

    2010-12-01

    Full Text Available Particle size reduction is a simple means to enhance the dissolution rate of poorly water soluble BCS-class II and IV drugs. However, the major drawback of this process is the possible introduction of process induced disorder. Drugs with different molecular arrangements may exhibit altered properties such as solubility and dissolution rate and, therefore, process induced solid state modifications need to be monitored. The aim of this study was two-fold: firstly, to investigate the dissolution rates of milled and unmilled simvastatin; and secondly, to screen for the main milling factors, as well as factor interactions in a dry ball milling process using simvastatin as model drug, and to optimize the milling procedure with regard to the opposing responses particle size and process induced disorder by application of a central composite face centered design. Particle size was assessed by scanning electron microscopy (SEM and image analysis. Process induced disorder was determined by partial least squares (PLS regression modeling of respective X-ray powder diffractograms (XRPD and Raman spectra. Valid and significant quadratic models were built. The investigated milling factors were milling frequency, milling time and ball quantity at a set drug load, out of which milling frequency was found to be the most important factor for particle size as well as process induced disorder. Milling frequency and milling time exhibited an interaction effect on the responses. The optimum milling settings using the maximum number of milling balls (60 balls with 4 mm diameter was determined to be at a milling frequency of 21 Hz and a milling time of 36 min with a resulting primary particle size of 1.4 μm and a process induced disorder of 6.1% (assessed by Raman spectroscopy and 8.4% (assessed by XRPD, at a set optimization limit of < 2 μm for particle size and < 10% for process induced disorder. This optimum was tested experimentally and the process induced disorder

  2. Images in Christmas Balls

    OpenAIRE

    van Beveren, Eef; Kleefeld, Frieder; Rupp, George

    2005-01-01

    We describe light-reflection properties of spherically curved mirrors, like balls in the Christmas tree. In particular, we study the position of the image which is formed somewhere beyond the surface of a spherical mirror, when an eye observes the image of a pointlike light source. The considered problem, originally posed by Abu Ali Hasan Ibn al-Haitham -- alias Alhazen -- more than a millennium ago, turned out to have the now well known analytic solution of a biquadratic equation, being stil...

  3. Ball Lightning Investigations

    Science.gov (United States)

    Bychkov, V. L.; Nikitin, A. I.; Dijkhuis, G. C.

    Ball lightning (BL) researches' review and theoretical models of three different authors are presented. The general review covers investigations from 1838 until the present day, and includes a discussion on observation data, experimental modeling, and theoretical approaches. Section 6.1 is written by Bychkov and Nikitin; authors of the sections 6.2, 6.3 and 6.4 are, respectively, Bychkov, Nikitin and Dijkhuis.

  4. Rock Characteristics and Ball Mill Energy Requirements at ...

    African Journals Online (AJOL)

    Goldfields Ghana Limited, Tarkwa Gold Mine (TGM), processes ores which occur in conglomerate reefs. The competence of the ore was observed to increase with increasing mining depth. Other rock properties such as porosity, micro-cracks and gold dissolution were also observed to change with depth. It therefore became ...

  5. Mechanocatalytic Production of Lactic Acid from Glucose by Ball Milling

    Directory of Open Access Journals (Sweden)

    Luyang Li

    2017-06-01

    Full Text Available A solvent-free process was developed for the direct production of lactic acid from glucose in a mechanocatalytic process in the presence of Ba(OH2, and a moderate lactic acid yield of 35.6% was obtained. Glucose conversion and lactic acid formation were favorable at higher catalyst/glucose mass ratios. However, at relatively lower catalyst/glucose mass ratios, they were greatly inhibited, and the promotion of fructose formation was observed. The mechanocatalytic process was applicable for various carbohydrates such as C5 sugars, C6 sugars, and disaccharides with 20–36% lactic acid yields achieved. This work provides a new pathway for the production of value-added chemicals from biomass resources.

  6. Rock Characteristics and Ball Mill Energy Requirements at ...

    African Journals Online (AJOL)

    Michael

    2015-06-01

    Jun 1, 2015 ... essentially of both rounded and angular quartz pebbles of varying sizes in a matrix which is highly silicified (Kesse, 1985). Faulting, fracturing and primary lithological permeability also modify the depth to porosity relationship. With prolonged operation of Goldfields Ghana. Limited, Tarkwa Gold Mine (TGM); ...

  7. The implementation of HPGR mills in existing grinding circuits

    Energy Technology Data Exchange (ETDEWEB)

    Patzelt, N.; Knecht, J.; Longhurst, D. [Krupp Polysius AG, Beckum (Germany)

    1996-12-31

    High pressure grinding mills have been successfully introduced in the industry. They offer the possibilities for capacity increase of existing plants and reduction of operating costs. The plants in operation are running in different applications and modes of operation. They can be installed in a combination with SAG and ball mills or in a stand-alone mode. In combination with other grinding mills, it has to be investigated how the HPGR can be installed to reach the full efficiency. This paper describes the possibilities of implementing high pressure grinding rolls and shows by case studies the potential of savings which could be reached.

  8. Chatter Prediction for Variable Pitch and Variable Helix Milling

    Directory of Open Access Journals (Sweden)

    Yong Wang

    2015-01-01

    Full Text Available Regenerative chatter is a self-excited vibration that can occur during milling, which shortens the lifetime of the tool and results in unacceptable surface quality. In this paper, an improved semidiscretization method for modeling and simulation with variable pitch and variable helix milling is proposed. Because the delay between each flute varies along the axial depth of the tool in milling, the cutting tool is discrete into some axial layers to simplify calculation. A comparison of the predicted and observed performance of variable pitch and variable helix against uniform pitch and uniform helix milling is presented. It is shown that variable pitch and variable helix milling can obtain larger stable cutting area than uniform pitch and uniform helix milling. Thus, it is concluded that variable pitch and variable helix milling are an effective way for suppressing chatter.

  9. A Vibrating Wire System For Quadrupole Fiducialization

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Zachary

    2010-12-13

    A vibrating wire system is being developed to fiducialize the quadrupoles between undulator segments in the LCLS. This note provides a detailed analysis of the system. The LCLS will have quadrupoles between the undulator segments to keep the electron beam focused. If the quadrupoles are not centered on the beam axis, the beam will receive transverse kicks, causing it to deviate from the undulator axis. Beam based alignment will be used to move the quadrupoles onto a straight line, but an initial, conventional alignment must place the quadrupole centers on a straight line to 100 {micro}m. In the fiducialization step of the initial alignment, the position of the center of the quadrupole is measured relative to tooling balls on the outside of the quadrupole. The alignment crews then use the tooling balls to place the magnet in the tunnel. The required error on the location of the quadrupole center relative to the tooling balls must be less than 25 {micro}m. In this note, we analyze a system under construction for the quadrupole fiducialization. The system uses the vibrating wire technique to position a wire onto the quadrupole magnetic axis. The wire position is then related to tooling balls using wire position detectors. The tooling balls on the wire position detectors are finally related to tooling balls on the quadrupole to perform the fiducialization. The total 25 {micro}m fiducialization error must be divided between these three steps. The wire must be positioned onto the quadrupole magnetic axis to within 10 {micro}m, the wire position must be measured relative to tooling balls on the wire position detectors to within 15 {micro}m, and tooling balls on the wire position detectors must be related to tooling balls on the quadrupole to within 10 {micro}m. The techniques used in these three steps will be discussed. The note begins by discussing various quadrupole fiducialization techniques used in the past and discusses why the vibrating wire technique is our method

  10. Magnetic properties of barium ferrite after milling by high energy milling (hem

    Directory of Open Access Journals (Sweden)

    Idayanti Novrita

    2017-01-01

    Full Text Available Magnetic properties of barium ferrite that were mashed by High Energy Milling (HEM has been characterized. The starting iron oxide powder (Fe2O3 and barium carbonate (BaCO3 were prepared by powder metallurgy technique by the stages of mixing, calcining, milling, compacting, and sintering. Weight ratio of Fe2O3: BaCO3 was 88.74 wt% : 17.52 wt%. Some additives such as calcium oxide (CaO, silicon dioxide (SiO2, and polyvinyl alcohol (PVA were added after calcining process. Milling by HEM was varied at 30, 60, 90, 120, and 150 minutes. The ball and container of HEM were made of stainless steel. Characterization micro structure by SEM showed that the milling time affect the grain size of the magnetic powder. The longer of milling time, the grain size was smaller and uniform. Characterization by using magnetic instrument Permagraph showed that the grain size will affect the magnetic properties of barium ferrite. Induction of remanence (Br, coercivity (HcJ, and product energy maximum (BHmax values increased with increasing milling time. The optimal magnetic properties were obtained at the time of milling 120 minutes with value of Hc = 1.97 kG, HcJ = 2.314 kOe, and BHmax = 0.64 MGOe.

  11. Physics in a Glitter Ball

    Science.gov (United States)

    Trikosko, Walter

    2011-01-01

    Maui Toys' Water Bouncer (Fig. 1) is a water-filled ball containing glitter. Buy one and put it on your desk and students can't keep their hands off of it. Pitch the ball in the air giving it a quick spin. When you catch it you will see a sparkling vortex. Twist the ball around different ways and the angular momentum of the fluid keeps the axis of…

  12. BLEACHING NEPTUNE BALLS

    Directory of Open Access Journals (Sweden)

    BONET Maria Angeles

    2014-05-01

    Full Text Available Posidonia Oceanic is a seaweed from Mediterranean Sea and it is more concentrated at the Balerian SEA. This implies the Valencian Community also. It forms vaste underwater meadows in the sea and are part of the Mediterranean ecosystem. It is a sea-grass specie with fruits and flowers. Leaves are ribbon-like and they grow in winter and at the end of summer some of them are separated and arrive to some sea line. Fuit is separated and can floate, it is known as “the olive of the sea” mainly in Italy, or as the Neptune Balls. As it can be used in different fields, it is is being studied in order ro have the precitice tests. Some authors have reported the manufacturing of fully bio-based comites with a gluten matrix by hot-press molding. And it has been considered as an effective insulator for building industry or even though to determine the presence of mercure in the Mediterranean sea some years ago. As many applications can be designed from that fibers, it has been considered to be bleached in order to used them in fashionable products. Consequently, its original brown color is not the most suitable one and it should be bleached as many other cellulosic fibers. The aim of this paper is to bleache neptune balls however, the inner fibers were not accessible at all and it implied not to bleach the inner fibers in the neptune ball. Further studiesd will consider bleaching the individualized fibers.

  13. Ovaler Ball, insbesondere Rugbyball

    OpenAIRE

    Grün, T. von der; Franke, N.

    2008-01-01

    DE 102008052621 A1 UPAB: 20100514 NOVELTY - The ball (1) has an electronic component arranged inside a shell (4), held in a preset position, and fastened in a region of a conical end, in a form-fit or firmly bonded manner. The conical end is provided with reinforcements. The electronic component is inserted in a lug (5) formed in the region. The shell is formed as a carcass-like outer shell. The electronic component is formed as a two-dimensional electronic module (6) provided as a transmitte...

  14. Individual ball possession in soccer.

    Directory of Open Access Journals (Sweden)

    Daniel Link

    Full Text Available This paper describes models for detecting individual and team ball possession in soccer based on position data. The types of ball possession are classified as Individual Ball Possession (IBC, Individual Ball Action (IBA, Individual Ball Control (IBC, Team Ball Possession (TBP, Team Ball Control (TBC und Team Playmaking (TPM according to different starting points and endpoints and the type of ball control involved. The machine learning approach used is able to determine how long the ball spends in the sphere of influence of a player based on the distance between the players and the ball together with their direction of motion, speed and the acceleration of the ball. The degree of ball control exhibited during this phase is classified based on the spatio-temporal configuration of the player controlling the ball, the ball itself and opposing players using a Bayesian network. The evaluation and application of this approach uses data from 60 matches in the German Bundesliga season of 2013/14, including 69,667 IBA intervals. The identification rate was F = .88 for IBA and F = .83 for IBP, and the classification rate for IBC was κ = .67. Match analysis showed the following mean values per match: TBP 56:04 ± 5:12 min, TPM 50:01 ± 7:05 min and TBC 17:49 ± 8:13 min. There were 836 ± 424 IBC intervals per match and their number was significantly reduced by -5.1% from the 1st to 2nd half. The analysis of ball possession at the player level indicates shortest accumulated IBC times for the central forwards (0:49 ± 0:43 min and the longest for goalkeepers (1:38 ± 0:58 min, central defenders (1:38 ± 1:09 min and central midfielders (1:27 ± 1:08 min. The results could improve performance analysis in soccer, help to detect match events automatically, and allow discernment of higher value tactical structures, which is based on individual ball possession.

  15. The influence of milling on the dissolution performance of simvastatin

    DEFF Research Database (Denmark)

    Zimper, Ulrike; Aaltonen, Jaakko; Krauel-Goellner, Karen

    2012-01-01

    , as well as factor interactions in a dry ball milling process using simvastatin as model drug, and to optimize the milling procedure with regard to the opposing responses particle size and process induced disorder by application of a central composite face centered design. Particle size was assessed...... properties such as solubility and dissolution rate and, therefore, process induced solid state modifications need to be monitored. The aim of this study was two-fold: firstly, to investigate the dissolution rates of milled and unmilled simvastatin; and secondly, to screen for the main milling factors...... by scanning electron microscopy (SEM) and image analysis. Process induced disorder was determined by partial least squares (PLS) regression modeling of respective X-ray powder diffractograms (XRPD) and Raman spectra. Valid and significant quadratic models were built. The investigated milling factors were...

  16. Solid-state vitrification of crystalline griseofulvin by mechanical milling.

    Science.gov (United States)

    Willart, Jean-François; Carpentier, Laurent; Danède, Florence; Descamps, Marc

    2012-04-01

    The thermodynamic, dynamic, and structural changes of crystalline griseofulvin upon high-energy ball milling at room temperature have been studied. The investigations have been performed by differential scanning calorimetry (DSC), dielectric relaxation spectroscopy, and powder X-ray diffraction. The results indicate that this compound undergoes a direct crystal-to-glass transformation upon milling, whereas no glass transition can be clearly detected upon heating because of the exceptional sub-glass transition temperature (T(g) ) recrystallization of the milled sample. This intrinsic difficulty for characterizing the glassy state has been overcome using three independent strategies: (i) comparison of the evolutions upon milling of both the crystalline powder and the quenched liquid, (ii) use of fast DSC to delay the recrystallization event, and (iii) search for dielectric β relaxations typical of glasses in the milled compound. Copyright © 2012 Wiley Periodicals, Inc.

  17. Investigation of a Ball Screw Feed Drive System Based on Dynamic Modeling for Motion Control

    Directory of Open Access Journals (Sweden)

    Yi-Cheng Huang

    2017-06-01

    Full Text Available This paper examines the frequency response relationship between the ball screw nut preload, ball screw torsional stiffness variations and table mass effect for a single-axis feed drive system. Identification for the frequency response of an industrial ball screw drive system is very important for the precision motion when the vibration modes of the system are critical for controller design. In this study, there is translation and rotation modes of a ball screw feed drive system when positioning table is actuated by a servo motor. A lumped dynamic model to study the ball nut preload variation and torsional stiffness of the ball screw drive system is derived first. The mathematical modeling and numerical simulation provide the information of peak frequency response as the different levels of ball nut preload, ball screw torsional stiffness and table mass. The trend of increasing preload will indicate the abrupt peak change in frequency response spectrum analysis in some mode shapes. This study provides an approach to investigate the dynamic frequency response of a ball screw drive system, which provides significant information for better control performance when precise motion control is concerned.

  18. Catching a gently thrown ball

    NARCIS (Netherlands)

    Lopez-Moliner, J.; Brenner, E.; Louw, S.; Smeets, J.B.J.

    2010-01-01

    Several studies have shown that people can catch a ball even if it is visible only during part of its flight. Here, we examine how well they can do so. We measured the movements of a ball and of the hands of both the thrower and the catcher during one-handed underarm throwing and catching. The

  19. Reflections on a Bouncing Ball

    Science.gov (United States)

    Rohr, Jim; Lopez, Veronica; Rohr, Tyler

    2014-01-01

    While observing the bounce heights of various kinds of sports balls dropped from different heights onto a variety of surfaces, we thought of the following question: Could measurements of drop and bounce heights of balls of different diameters, but of the same material, falling from different heights, but on the same surface, be expressed by a…

  20. Structure of laboratory ball lightning

    Science.gov (United States)

    Ito, Tsuyohito; Tamura, Tomoya; Cappelli, Mark A.; Hamaguchi, Satoshi

    2009-12-01

    Trajectories of self-sustained laboratory ball lightning, generated by arc discharges with silicon, are investigated for understanding the possibility of buoyant flight. Extremely low apparent densities are found, nearly approaching that of standard air. The freely buoyant balls are observed to survive for about 0.1 s, with significantly buoyant balls surviving for several seconds. These ball lightning objects are found to have a density and size that can easily allow them to be carried by a gentle breeze of a few meters per second. The results are interpreted by a model that is an extension of that first proposed by Abrahamson and Dinniss [J. Abrahamson and J. Dinniss, Nature (London) 403, 519 (2000)]. The buoyant behavior of ball lightning seen in our experiments is believed to arise as a result of the formation of a nanoparticle oxide network growing from a molten silicon core.

  1. Eddy Current Model of Ball Lightning

    OpenAIRE

    Shelton, J. D.

    2011-01-01

    Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.

  2. Unravelling the relationship between degree of disorder and the dissolution behavior of milled glibenclamide

    DEFF Research Database (Denmark)

    Mah, Pei T; Laaksonen, Timo; Rades, Thomas

    2014-01-01

    Milling is an attractive method to prepare amorphous formulations as it does not require the use of solvents and is suitable for thermolabile drugs. One of the key critical quality attributes of milled amorphous formulations is their dissolution behavior. However, there are limited studies...... that have investigated the relationship between degree of disorder induced by milling and dissolution behavior. The main aim of this study was to identify the analytical technique used to characterize degree of disorder that correlates best with the recrystallization behavior during dissolution of milled...... glibenclamide samples. Solid state and surface changes during dissolution of milled glibenclamide samples were monitored in order to elucidate the processes that influence the dissolution behavior of milled glibenclamide samples. Glibenclamide was ball milled for different durations and analyzed using X...

  3. Unsolved Mystery of Ball Lightning

    Science.gov (United States)

    Bychkov, V. L.

    Ball lightning is an unusual phenomenon always drawing attention of people. There are still questions about its origination, features, interaction with environment, and phenomena related to it. On a way of studying this phenomenon, there are a lot of difficulties, the basic of them is insufficiency of authentic, scientific data. The chapter sets as the purpose to interest the reader in the problem, to describe conditions of ball lightning occurrence, theories, and its hypotheses explanation, to include readers in a circle of experimental searches in creation of a ball lightning and its analogues, and to describe fascination of a problem and difficulty of its solution.

  4. Steel mill products analysis using qualities methods

    Directory of Open Access Journals (Sweden)

    B. Gajdzik

    2016-10-01

    Full Text Available The article presents the subject matter of steel mill product analysis using quality tools. The subject of quality control were bolts and a ball bushing. The Pareto chart and fault mode and effect analysis (FMEA were used to assess faultiness of the products. The faultiness analysis in case of the bolt enabled us to detect the following defects: failure to keep the dimensional tolerance, dents and imprints, improper roughness, lack of pre-machining, non-compatibility of the electroplating and faults on the surface. Analysis of the ball bushing has also revealed defects such as: failure to keep the dimensional tolerance, dents and imprints, improper surface roughness, lack of surface premachining as well as sharp edges and splitting of the material.

  5. EFFECT OF CUP AND BALL TYPES ON MECHANO-CHEMICAL SYNTHES IS OF Al2O3–TiC NANOCOMPOSITE POWDER

    Directory of Open Access Journals (Sweden)

    M. Zakeri

    2012-07-01

    Full Text Available Al2O3–TiC nanocomposite powder was successfully synthesized by ball milling TiO2, Al and graphite powders. Effects of cup and ball type, milling time and annealing were investigated. XRD was used to characterize milled and annealed powders. The morphological and microstructural evolutions were studied by SEM and TEM. Results showed that the formation of this composite begins after 20 h and completes after 35 h of milling with stainless steel cup and balls. In contrast, there is no reaction during milling (up to 80 h with ZrO2 cup and balls. Fe and ZrO2 were the major impurities introduced during milling with stainless steel and ZrO2 cups, respectively. The Fe impurity was removed by leaching in 3HCl·HNO3 solution for 4 days. Mean grain size less than 7 nm was achieved at the end of milling. In spite of grain growth, this composite maintained its nanocrystalline nature after annealing at 1000°C.

  6. Synthesis of ZnO Nanocrystal-Graphene Composite by Mechanical Milling and Sonication-Assisted Exfoliation

    Science.gov (United States)

    Arora, Sweety; Srivastava, Chandan

    2017-02-01

    A ZnO nanocrystal-graphene composite was synthesized by a two-step method involving mechanical milling and sonication-assisted exfoliation. Zn metal powder was first ball-milled with graphite powder for 30 h in water medium. This ball-milled mixture was then subjected to exfoliation by sonication in the presence of sodium lauryl sulfate surfactant to produce graphene decorated with spherical agglomerates of ultrafine nanocrystalline ZnO. The presence of a few layers of graphene was confirmed by Raman spectroscopy and atomic force microscopy measurements. The size, phase identity and composition of the ZnO nanocrystals was determined by transmission electron microscopy measurements.

  7. Enhancing the Bounce of a Ball

    Science.gov (United States)

    Cross, Rod

    2010-01-01

    In sports such as baseball, softball, golf, and tennis, a common objective is to hit the ball as fast or as far as possible. Another common objective is to hit the ball so that it spins as fast as possible, since the trajectory of the ball through the air is strongly affected by ball spin. In an attempt to enhance both the coefficient of…

  8. Micromilling of Ti-6Al-4V Titanium Alloy Using Ball-end Tool

    Science.gov (United States)

    Pratap, T.; Patra, K.

    2017-09-01

    The present work experimentally investigates the characteristics of micromilling of Ti-6Al-4V workpiece using ball-end tool. Micromilling were performed using 400 ¼m ball-end milling tool with the consideration of effective tool diameter. The effective tool diameter in ball-end milling is different from flat-end milling due to variation in cutting zone with axial depth of cut which accounts actual cutting speed and feed the machining. Process input variables includes cutting speed, feed per tooth and axial depth of cut, each with three levels, whereas cutting forces and surface roughness as process responses. Response surface methodology (RSM) based quadratic regression analysis was utilized to develop the correlation between process inputs and responses. Experimental results of present study on micromilling of Ti-6Al-4V using ball-end tool showed that axial depth of cut and feed per tooth could significantly influence the cutting forces and surface roughness. However, present study shows cutting speed has least effect on process responses. Finally, suitable set of process variables were proposed based multi objective optimization approach to obtain minimum cutting forces and surface roughness which were also validated with conformation test results.

  9. LHC gets the ball rolling

    CERN Multimedia

    2007-01-01

    A technique involving a small ball with a transmitter embedded inside it has been successfully tested in Sector 7-8. The ball is sent through the LHC beam pipes to check the LHC interconnections. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI). During the tests the ball is inserted very carefully into the vacuum chamber.A game of ping-pong at the LHC? On 13 September a rather unusual test was carried out in Sector 7-8 of the accelerator. A ball just a bit smaller than a ping-pong ball was carefully introduced into one of the accelerator’s two vacuum pipes, where it travelled 800 metres in the space of a few mi...

  10. Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

    Science.gov (United States)

    Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

    2018-01-01

    Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, ;sub-sampling training examples;-based and ;manipulating input features;-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

  11. Nanostructuring of Undoped ZnSb by Cryo-Milling

    Science.gov (United States)

    Song, X.; Valset, K.; Graff, J. S.; Thøgersen, A.; Gunnæs, A. E.; Luxsacumar, S.; Løvvik, O. M.; Snyder, G. J.; Finstad, T. G.

    2015-08-01

    We report the preparation of nanosized ZnSb powder by cryo-milling. The effect of cryo-milling then hot-pressing of undoped ZnSb was investigated and compared with that of room temperature ball-milling and hot-pressing under different temperature conditions. ZnSb is a semiconductor with favorable thermoelectric properties when doped. We used undoped ZnSb to study the effect of nanostructuring on lattice thermal conductivity, and with little contribution at room temperature from electronic thermal conductivity. Grain growth was observed to occur during hot-pressing, as observed by transmission electron microscopy and x-ray diffraction. The thermal conductivity was lower for cryo-milled samples than for room-temperature ball-milled samples. The thermal conductivity also depended on hot-pressing conditions. The thermal conductivity could be varied by a factor of two by adjusting the process conditions and could be less than a third that of single-crystal ZnSb.

  12. Influence of mechanical milling time on physicochemical properties and stability of cefotaxime sodium

    Directory of Open Access Journals (Sweden)

    Rouholamini Najafabadi A.

    2007-04-01

    Full Text Available The aim of this study was to examine the effect of mechanical milling time on physicochemical properties and stability of Cefotaxime sodium (CS. CS was micronized by ball milling in five period of time: 30, 60, 120, 240, and 360 min. The powder properties of the samples were examined by HPLC assay, laser diffraction, helium densitometery, IR spectrophotometery, X-ray diffraction (XRD, scaning electron microscopy (SEM, differential scanning calorimetery (DSC, thermogravimetric analysis (TGA and Karl-Fisher titrimetery. The results showed that ball milling was not an appropriate method for particle size reduction to make solid dosage form such as dry powder inhaler formulation (DPI of CS and by increase in milling time, degradation of CS increased.

  13. Modeling of Surface Geometric Structure State After Integratedformed Milling and Finish Burnishing

    Science.gov (United States)

    Berczyński, Stefan; Grochała, Daniel; Grządziel, Zenon

    2017-06-01

    The article deals with computer-based modeling of burnishing a surface previously milled with a spherical cutter. This method of milling leaves traces, mainly asperities caused by the cutting crossfeed and cutter diameter. The burnishing process - surface plastic treatment - is accompanied by phenomena that take place right in the burnishing ball-milled surface contact zone. The authors present the method for preparing a finite element model and the methodology of tests for the assessment of height parameters of a surface geometrical structure (SGS). In the physical model the workpieces had a cuboidal shape and these dimensions: (width × height × length) 2×1×4.5 mm. As in the process of burnishing a cuboidal workpiece is affected by plastic deformations, the nonlinearities of the milled item were taken into account. The physical model of the process assumed that the burnishing ball would be rolled perpendicularly to milling cutter linear traces. The model tests included the application of three different burnishing forces: 250 N, 500 N and 1000 N. The process modeling featured the contact and pressing of a ball into the workpiece surface till the desired force was attained, then the burnishing ball was rolled along the surface section of 2 mm, and the burnishing force was gradually reduced till the ball left the contact zone. While rolling, the burnishing ball turned by a 23° angle. The cumulative diagrams depict plastic deformations of the modeled surfaces after milling and burnishing with defined force values. The roughness of idealized milled surface was calculated for the physical model under consideration, i.e. in an elementary section between profile peaks spaced at intervals of crossfeed passes, where the milling feed fwm = 0.5 mm. Also, asperities after burnishing were calculated for the same section. The differences of the obtained values fall below 20% of mean values recorded during empirical experiments. The adopted simplification in after-milling

  14. Processing of Polysulfone to Free Flowing Powder by Mechanical Milling and Spray Drying Techniques for Use in Selective Laser Sintering

    Directory of Open Access Journals (Sweden)

    Nicolas Mys

    2016-04-01

    Full Text Available Polysulfone (PSU has been processed into powder form by ball milling, rotor milling, and spray drying technique in an attempt to produce new materials for Selective Laser Sintering purposes. Both rotor milling and spray drying were adept to make spherical particles that can be used for this aim. Processing PSU pellets by rotor milling in a three-step process resulted in particles of 51.8 μm mean diameter, whereas spray drying could only manage a mean diameter of 26.1 μm. The resulting powders were characterized using Differential Scanning Calorimetry (DSC, Gel Permeation Chromatography (GPC and X-ray Diffraction measurements (XRD. DSC measurements revealed an influence of all processing techniques on the thermal behavior of the material. Glass transitions remained unaffected by spray drying and rotor milling, yet a clear shift was observed for ball milling, along with a large endothermic peak in the high temperature region. This was ascribed to the imparting of an orientation into the polymer chains due to the processing method and was confirmed by XRD measurements. Of all processed powder samples, the ball milled sample was unable to dissolve for GPC measurements, suggesting degradation by chain scission and subsequent crosslinking. Spray drying and rotor milling did not cause significant degradation.

  15. Physical nature of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Stakhanov, I.P.

    1979-01-01

    An analysis is made of results obtained from the observations of ball lightning. Principal attention is given to data obtained during the last two decades. A brief critique is also offered on hypotheses about its origin. A more detailed presentation is made of the cluster hypothesis according to which ball lightning consists of complex compounds of ions and neutral molecules. The book is intended for a broad spectrum of readers, but is particularly directed toward those with a knowledge of physics and chemistry. 70 references, 24 figures, 17 tables.

  16. Ball lightning risk to aircraft

    Science.gov (United States)

    Doe, R.; Keul, A.

    2009-04-01

    Lightning is a rare but regular phenomenon for air traffic. Aircraft are designed to withstand lightning strikes. Research on lightning and aircraft can be called detailed and effective. In the last 57 years, 18 reported lightning aviation disasters with a fatality figure of at least 714 persons occurred. For comparison, the last JACDEC ten-year average fatality figure was 857. The majority encountered lightning in the climb, descent, approach and/or landing phase. Ball lightning, a metastable, rare lightning type, is also seen from and even within aircraft, but former research only reported individual incidents and did not generate a more detailed picture to ascertain whether it constitutes a significant threat to passenger and aircraft safety. Lacking established incident report channels, observations were often only passed on as "air-travel lore". In an effort to change this unsatisfactory condition, the authors have collected a first international dataset of 38 documented ball lightning aircraft incidents from 1938 to 2001 involving 13 reports over Europe, 13 over USA/Canada, and 7 over Russia. 18 (47%) reported ball lightning outside the aircraft, 18 (47%) inside, 2 cases lacked data. 8 objects caused minor damage, 8 major damage (total: 42%), only one a crash. No damage was reported in 18 cases. 3 objects caused minor crew injury. In most cases, ball lightning lasted several seconds. 11 (29%) incidents ended with an explosion of the object. A cloud-aircraft lightning flash was seen in only 9 cases (24%) of the data set. From the detailed accounts of air personnel in the last 70 years, it is evident that ball lightning is rarely, but consistently observed in connection with aircraft and can also occur inside the airframe. Reports often came from multiple professional witnesses and in several cases, damages were investigated by civil or military authorities. Although ball lightning is no main air traffic risk, the authors suggest that incident and accident

  17. A Ball in a Groove

    OpenAIRE

    Halsey, Thomas C.; Ertas, Deniz

    1999-01-01

    We study the static equilibrium of an elastic sphere held in a rigid groove by gravity and frictional contacts, as determined by contact mechanics. As a function of the opening angle of the groove and the tilt of the groove with respect to the vertical, we identify two regimes of static equilibrium for the ball. In the first of these, at large opening angle or low tilt, the ball rolls at both contacts as it is loaded. This is an analog of the "elastic" regime in the mechanics of granular medi...

  18. Research on the thermal load of CNC milling machine

    Science.gov (United States)

    Nie, Xue-Jun; Wu, Ping-Dong

    2011-05-01

    Machine tool accuracy is the assurance of top-quality products in machining processes. In the all kinds of errors related to machine tools, thermal errors of machine tools' parts play an important role in machining accuracy and directly influence both the surface finish and the geometric shape of the finished workpiece. Therefore the objective of this work was to analyze the temperature field and thermal deformation in some parts of CNC machine tools. In this paper, the thermal boundary condition of main spindle and driving ball screw in CNC milling machine are discussed, some parameters in heat transfer process are calculated. Based on steady heat transfer process, the thermal analysis about spindle and ball screw is carried out under ANSYS environment, and their temperature fields are obtained when milling machine is working. Then the deformations of main spindle and ball screw are acquired by applying the thermal structure coupling element. Furthermore, in order to decrease main parts' deformations and improve the accuracy of CNC milling machine, some suggests are proposed.

  19. Mechanically Milled Irregular Zinc Nanoparticles for Printable Bioresorbable Electronics.

    Science.gov (United States)

    Mahajan, Bikram K; Yu, Xiaowei; Shou, Wan; Pan, Heng; Huang, Xian

    2017-05-01

    Bioresorbable electronics is predominantly realized by complex and time-consuming anhydrous fabrication processes. New technology explores printable methods using inks containing micro- or nano-bioresorbable particles (e.g., Zn and Mg). However, these particles have seldom been obtained in the context of bioresorbable electronics using cheap, reliable, and effective approaches with limited study on properties essential to printable electronics. Here, irregular nanocrystalline Zn with controllable sizes and optimized electrical performance is obtained through ball milling approach using polyvinylpyrrolidone (PVP) as a process control agent to stabilize Zn particles and prevent cold welding. Time and PVP dependence of the ball milled particles are studied with systematic characterizations of morphology and composition of the nanoparticles. The results reveal crystallized Zn nanoparticles with a size of ≈34.834 ± 1.76 nm and low surface oxidation. The resulting Zn nanoparticles can be readily printed onto bioresorbable substrates and sintered at room temperature using a photonic sintering approach, leading to a high conductivity of 44 643 S m -1 for printable zinc nanoparticles. The techniques to obtain Zn nanoparticles through ball milling and processing them through photonic sintering may potentially lead to a mass fabrication method for bioresorbable electronics and promote its applications in healthcare, environmental protection, and consumer electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Modelling of a Bi-axial Vibration Energy Harvester

    Science.gov (United States)

    2013-05-01

    effect of the electrical load on the transduction, and on the mechanical dynamics. It was demonstrated that the back EMF from current flow in the...created with a permanent-magnet/ball-bearing arrangement. The mechanical oscillations of the ball-bearing in response to bi-axial vibrations in a host...system on an aircraft platform. Modelling of the mechanical dynamics and the electromechanical transduction of the harvester is undertaken by: means of

  1. FM Interviews: Stephanie Mills

    OpenAIRE

    Valauskas, Edward

    2002-01-01

    Stephanie Mills is an author, editor, lecturer and ecological activist who has concerned herself with the fate of the earth and humanity since 1969, when her commencement address at Mills College in Oakland, Calif., drew the attention of a nation. Her speech, which the New York Times called "perhaps the most anguished statement" of the year's crop of valedictory speeches, predicted a bleak future. According to Mills, humanity was destined for suicide, the result of overpopulation and overuse ...

  2. Generation of Laboratory Ball Lightning

    Energy Technology Data Exchange (ETDEWEB)

    Oreshko, A G [Moscow Aviation Institute (State Technical University), Volokolamskoe shosse 4, 125871 Moscow (Russian Federation)

    2006-07-15

    The phenomenon of energy conversion in the streams of directed electrons and ions into electromagnetic radiation was found out experimentally and proved theoretically. The direct proofs of the domain mechanism of the charged particles acceleration and mechanism of ball lightning generation were obtained and the theoretical calculations were refined.

  3. SECRET OF A BALL LIGHTNING

    Directory of Open Access Journals (Sweden)

    E.V. Savich

    2013-04-01

    Full Text Available A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming, in the end, the surrounding air into a steam cloud that transits into ferroelectric state under the magnetic field action.

  4. A Conjecture Concerning Ball Lightning

    OpenAIRE

    Sturrock, P. A.

    2016-01-01

    There is at present no theory that can explain the curious properties of ball lightning. This suggests that we may not be using the most appropriate concepts. The concept of a 'parallel space' may point the way to a valid theory.

  5. Idea Bank: Wiffle Ball Physics

    Science.gov (United States)

    Lancor, Rachael

    2009-01-01

    Projectile motion, a cornerstone topic of introductory physics, is usually a student's first exposure to the problem-solving techniques used in this subject. Often, this is an inactive learning experience--students work with pencil and paper to read and solve projectile motion problems (e.g., diagrams and descriptions of balls being hit, kicked,…

  6. LHC gets the ball rolling

    CERN Document Server

    2007-01-01

    1. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI).2. During the tests the ball is inserted very carefully into the vacuum chamber.1. Le groupe pluridisciplinaire qui a mené le projet de balle RF pour vérifier les interconnexions avec, de gauche à droite, Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS) et Marek Gasior (AB/BI).2. Lors des tests, la balle est insérée dans la chambre à vide avec beaucoup de précaution.

  7. Electron-Ionic Model of Ball Lightening

    OpenAIRE

    Fedosin, Sergey G.; Kim, Anatolii S.

    2001-01-01

    The model of ball lightning is presented where outside electron envelope is kept by inside volume of positive charges. The moving of electron in outside envelope is a reason of strong magnetic field, which controls the state of hot ionized air inside of ball lightning. The conditions of origins of ball lightning are investigated and the values of parameters for ball lightning of maximum power are calculated.

  8. Prediction of mill performance

    Energy Technology Data Exchange (ETDEWEB)

    P.A. Bennett [CoalTech Pty Ltd. (Australia)

    2005-07-01

    This Australian Coal Association Research Program (ACARP) project aimed to demonstrate that the Hardgrove Grindability Index (HGI) coupled with standard Petrographic Analysis can be used to greatly improve the prediction of mill power requirements, mill throughput and product size. The project examined the mill test data from ACIRL's pilot scale vertical spindle mill on 96 coals. A total of 360 mill tests, conducted under a wide range of throughputs, roll pressures and classifier settings, were included into the data set. The mill performance of maceral groups or microlithotypes was assumed to be additive, that is, each maceral group or microlithotype behaved independently and a size fraction of the product PF was the volume weighted sum of the petrographic components of that size fraction. Based on this assumption it was possible to determine the size distribution of the product PF, for a wide range of milling conditions, based solely on petrographic analysis. Microlithotypes were not determined directly but were estimated from the maceral analysis. The size distribution of individual maceral groups or microlithotypes can also be estimated based on developed correlations. Size distribution determined from petrographic analysis proved to be a better estimate than that determined from the HGI. Mill power can be estimated from petrographic analysis, but the HGI was found to be a better predictor of mill power. 19 refs., 4 figs., 1 tab.

  9. Galvanic Interaction between Chalcopyrite and Pyrite with Low Alloy and High Carbon Chromium Steel Ball

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2013-01-01

    Full Text Available This study was aimed to investigate the galvanic interaction between pyrite and chalcopyrite with two types of grinding media (low alloy and high carbon chromium steel ball in grinding of a porphyry copper sulphide ore. Results indicated that injection of different gases into mill altered the oxidation-reduction environment during grinding. High carbon chromium steel ball under nitrogen gas has the lowest galvanic current, and low alloy steel ball under oxygen gas had the highest galvanic current. Also, results showed that the media is anodic relative to pyrite and chalcopyrite, and therefore pyrite or chalcopyrite with a higher rest potential acted as the cathode, whilst the grinding media with a lower rest potential acted as the anode, when they are electrochemically contacted. It was also found that low alloy steel under oxygen produced the highest amount of EDTA extractable iron in the slurry, whilst high carbon chromium steel under nitrogen atmosphere led to the lowest amount.

  10. Ceramic ball grid array package stress analysis

    Science.gov (United States)

    Badri, S. H. B. S.; Aziz, M. H. A.; Ong, N. R.; Sauli, Z.; Alcain, J. B.; Retnasamy, V.

    2017-09-01

    The ball grid array (BGA), a form of chip scale package (CSP), was developed as one of the most advanced surface mount devices, which may be assembled by an ordinary surface ball bumps are used instead of plated nickel and gold (Ni/Au) bumps. Assembly and reliability of the BGA's printed circuit board (PCB), which is soldered by conventional surface mount technology is considered in this study. The Ceramic Ball Grid Array (CBGA) is a rectangular ceramic package or square-shaped that will use the solder ball for external electrical connections instead of leads or wire for connections. The solder balls will be arranged in an array or grid at the bottom of the ceramic package body. In this study, ANSYS software is used to investigate the stress on the package for 2 balls and 4 balls of the CBGA package with the various force range of 1-3 Newton applied to the top of the die, top of the substrate and side of the substrate. The highest maximum stress was analyzed and the maximum equivalent stress was observed on the solder ball and the die. From the simulation result, the CBGA package with less solder balls experience higher stress compared to the package with many solder balls. Therefore, less number of solder ball on the CBGA package results higher stress and critically affect the reliability of the solder balls itself, substrate and die which can lead to the solder crack and also die crack.

  11. Ni-Mn-Sn Heusler: milling and annealing effect on structural and magnetic properties

    Science.gov (United States)

    Popa, Florin; Florin Marinca, Traian; Florin Chicinaş, Horea; Isnard, Olivier; Chicinaş, Ionel

    2017-10-01

    Nanocrystalline Ni51Mn19Sn30 Heusler alloy was prepared in the form of powder by solid state reaction in a planetary ball mill under argon atmosphere. After 10 h of milling the samples exhibit a mixture of two phases: disordered Heusler structure and half-Heusler structure. The stability of the phases was studied and a transformation of the disordered Heusler phase into the ordered Heusler and Ni3Sn2 phase was observed after heat treatment. Magnetic properties strongly depend on the phases promoted during milling and annealing. The phase change after annealing leads to the increase of the sample’s magnetisation.

  12. Magnetic structure evolution in mechanically milled nanostructured ZnFe2O4 particles

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Wynn, P.; Mørup, Steen

    1999-01-01

    Nanostructured partially-inverted ZnFe2O4 particles have been prepared from bulk ZnFe2O4 by high-energy ball milling in an open container. The grain size reduction, cation site distributions, and the evolution of magnetic structures have been studied by x-ray diffraction with Rietveld structure...

  13. Effect of milling on the magnetic properties of Al-Mn obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Betancourt, Mirna, E-mail: betamirna@gmail.com [Instituto Universitario de Tecnologia Cumana (Venezuela, Bolivarian Republic of); Instituto Venezolano de Investigaciones Cientificas, Lab. Materiales, Centro Ingenieria de Materiales y Nanotecnologia (Venezuela, Bolivarian Republic of); Silva, Pedro [Instituto Venezolano de Investigaciones Cientificas, Lab. Materia Condensada, Centro de Fisica (Venezuela, Bolivarian Republic of); Gonzalez, Gema, E-mail: gemagonz@ivic.gob.ve [Instituto Venezolano de Investigaciones Cientificas, Lab. Materiales, Centro Ingenieria de Materiales y Nanotecnologia (Venezuela, Bolivarian Republic of)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Al-42 at.% Mn transforms to {alpha}-Mn(Al) by mechanical milling after 5 h of milling. Black-Right-Pointing-Pointer Transformation to nano {beta}-Mn is reached after 50 h of milling with 6 nm grain size. Black-Right-Pointing-Pointer Milling strongly affects magnetic behavior. - Abstract: Al-Mn powders were prepared to obtain the compound Mn{sub 42}Al{sub 58} by mechanical alloying. The powders were milled during different periods (1 h, 5 h, 11.5 h, 15 h, 20 h and 50 h) using a SPEX 8000 mixer mill in nitrogen atmosphere. The materials were characterized by X-ray diffraction (XRD) and magnetic properties at room temperature, using a vibrating sample magnetometer (VSM). XRD shows partial transformation to {alpha}-Mn after only 1 h of milling and a mixture of {alpha}-Mn and {beta}-Mn after 11.5 h of milling and further milling resulted in transformation to {beta}-Mn phase with a grain size of 6 nm after 50 h. The change in magnetic properties with milling time is quite dramatic, from a ferromagnetic behavior for {alpha}-Mn(Al) to paramagnetic after 11.5 h of milling and showing again ferromagnetic behavior, with a strong increase of magnetization values of 5.5 emu/g, after 50 h of milling with formation of {beta}-Mn(Al).

  14. Ceramic Rail-Race Ball Bearings

    Science.gov (United States)

    Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.

    2010-01-01

    Non-lubricated ball bearings featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball bearing, the proposed bearing would include an inner and an outer ring separated by balls in rolling contact with the races. However, unlike a conventional ball bearing, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls

  15. Polymer-composite ball lightning.

    Science.gov (United States)

    Bychkov, V L

    2002-01-15

    Investigations into the state of ball lightning (BL) have been made, and both theory and experiments, related to so-called "polymer-composite" ball lightning, are presented. The properties of such a polymeric BL have been described and are that of a long-lived object capable of storing high energy. Results of experiments, starting with polymeric components in erosive gas discharge experiments, are described and discussed. The model of BL as a highly charged polymer-dielectric structure is described. According to this model BL appears as the result of the aggregation of natural polymers, such as lignin and cellulose, soot, polymeric silica and other natural dust particles. Its ability to glow is explained by the appearance over its perimeter of gas discharges near the highly charged BL surface, and electrical breakdown of some regions on the surface, consisting of polymerized and aggregated threads.

  16. How to create ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1991-01-01

    Procedures are given on how to produce ball lightning. Necessary equipment includes a transformer of 150,000 watts capable of providing approximately 10,000 amperes at 15 volts, 60 cycles; thick one inch cables of stranded wire leading into a 3 by 4 by 1 foot plastic tank; a quarter inch thick 4 by 6 inch aluminum plate to be used as one of the discharge electrodes; and another electrode of heavy copper wire with the insulation stripped back 6 inches.

  17. Measurements of drag and lift on smooth balls in flight

    Science.gov (United States)

    Cross, Rod; Lindsey, Crawford

    2017-07-01

    Measurements are presented on the drag and lift coefficients for three relatively smooth balls launched in air and tracked with two cameras separated horizontally by 6.4 m. The ball spin was varied in order to investigate whether the Magnus force would increase or decrease when the ball spin was increased. For one ball, the Magnus force increased. For another ball, the Magnus force decreased almost to zero after reaching a maximum. For the third ball, the Magnus force was negative at low ball spins and positive at high ball spins. For one of the balls, the ball spin increased with time as it travelled through the air.

  18. Microstructure And Thermoelectric Properties Of Tags-90 Compounds Fabricated By Mechanical Milling Process

    Directory of Open Access Journals (Sweden)

    Kim H.-S

    2015-06-01

    Full Text Available TAGS-90 compound powder was directly prepared from the elements by high-energy ball milling (HEBM and subsequently consolidated by a spark plasma sintering (SPS. Effect of milling time on the microstructure and thermoelectric properties of the samples were investigated. The particle size of fabricated powders were decreased with increasing milling time, finally fine particles with ~1μm size was obtained at 90 min. The SPS samples exhibited higher relative densities (>99% with fine grain size. X-ray diffraction analysis (XRD and energy dispersion analysis (EDS results revealed that all the samples were single phase of GeTe with exact composition. The electrical conductivity of samples were decreased with milling time, whereas Seebeck coefficient increased over the temperature range of RT~450°C. The highest power factor was 1.12×10−3W/mK2 obtained for the sample with 90 min milling at 450°C.

  19. Keeping your eyes continuously on the ball while running for catchable and uncatchable fly balls.

    Science.gov (United States)

    Postma, Dees B W; den Otter, A Rob; Zaal, Frank T J M

    2014-01-01

    When faced with a fly ball approaching along the sagittal plane, fielders need information for the control of their running to the interception location. This information could be available in the initial part of the ball trajectory, such that the interception location can be predicted from its initial conditions. Alternatively, such predictive information is not available, and running to the interception location involves continuous visual guidance. The latter type of control would predict that fielders keep looking at the approaching ball for most of its flight, whereas the former type of control would fit with looking at the ball during the early part of the ball's flight; keeping the eyes on the ball during the remainder of its trajectory would not be necessary when the interception location can be inferred from the first part of the ball trajectory. The present contribution studied visual tracking of approaching fly balls. Participants were equipped with a mobile eye tracker. They were confronted with tennis balls approaching from about 20 m, and projected in such a way that some balls were catchable and others were not. In all situations, participants almost exclusively tracked the ball with their gaze until just before the catch or until they indicated that a ball was uncatchable. This continuous tracking of the ball, even when running close to their maximum speeds, suggests that participants employed continuous visual control rather than running to an interception location known from looking at the early part of the ball flight.

  20. Keeping your eyes continuously on the ball while running for catchable and uncatchable fly balls.

    Directory of Open Access Journals (Sweden)

    Dees B W Postma

    Full Text Available When faced with a fly ball approaching along the sagittal plane, fielders need information for the control of their running to the interception location. This information could be available in the initial part of the ball trajectory, such that the interception location can be predicted from its initial conditions. Alternatively, such predictive information is not available, and running to the interception location involves continuous visual guidance. The latter type of control would predict that fielders keep looking at the approaching ball for most of its flight, whereas the former type of control would fit with looking at the ball during the early part of the ball's flight; keeping the eyes on the ball during the remainder of its trajectory would not be necessary when the interception location can be inferred from the first part of the ball trajectory. The present contribution studied visual tracking of approaching fly balls. Participants were equipped with a mobile eye tracker. They were confronted with tennis balls approaching from about 20 m, and projected in such a way that some balls were catchable and others were not. In all situations, participants almost exclusively tracked the ball with their gaze until just before the catch or until they indicated that a ball was uncatchable. This continuous tracking of the ball, even when running close to their maximum speeds, suggests that participants employed continuous visual control rather than running to an interception location known from looking at the early part of the ball flight.

  1. Monitoring vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Tiryaki, B. [Hacettepe University (Turkey). Dept. of Mining Engineering

    2003-12-01

    The paper examines the prediction and optimisation of machine vibrations in longwall shearers. Underground studies were carried out at the Middle Anatolian Lignite Mine, between 1993 and 1997. Several shearer drums with different pick lacing arrangements were designed and tested on double-ended ranging longwall shearers employed at the mine. A computer program called the Vibration Analysis Program (VAP) was developed for analysing machine vibrations in longwall shearers. Shearer drums that were tested underground, as well as some provided by leading manufacturers, were analyzed using these programs. The results of the experiments and computer analyses are given in the article. 4 refs., 9 figs.

  2. Requerimientos tecnológicos del transportador de laterita hacia el molino de bolas, de la Empresa Productora de Níquel Comandante Ernesto Guevara; Technological Requirements of the Conveyor Belt which Carries Laterite to the Balls Mill in Nickel Producer

    Directory of Open Access Journals (Sweden)

    Javier Muñoz Álvarez

    2011-02-01

    Full Text Available Se describe el flujo productivo existente en la Empresa Productora del Níquel Comandante Ernesto Guevara,hasta la etapa de la molienda seca, con énfasis en los detalles técnicos de mayor relevancia en el proceso.Se analiza la influencia de la cantidad de mineral en el sistema sobre el comportamiento energético de lamolienda. Finalmente se determinan los requerimientos tecnológicos impuestos por el transportador delaterita 215 - TR - 201 al accionamiento eléctrico, en función de las características y las necesidades delproceso. In the paper, the productive flow existing in the nickel producer enterprise Commandant Ernesto Guevarawas described until the stage of dry milling, with an emphasis on the technical details of greater relevancy inthe process. There was analyzed the influence of the amount of mineral in the system over the energyconsumption performance of the milling. Finally it were identified the technological requirements imposed bythe 215 - TR - 201 laterite carrier to the electric drive, according to the characteristics and needs of theprocess.

  3. Prognostics Health Management of Electronic Systems Under Mechanical Shock and Vibration Using Kalman Filter Models and Metrics

    Data.gov (United States)

    National Aeronautics and Space Administration — Structural damage to ball grid array interconnects incurred during vibration testing has been monitored in the prefailure space using resistance spectroscopy-based...

  4. Full Dynamic Ball Bearing Model with Elastic Outer Ring for High Speed Applications

    Directory of Open Access Journals (Sweden)

    Christian Wagner

    2017-06-01

    Full Text Available Ball bearings are commonly used in high speed turbomachinery and have a critical influence on the rotordynamic behavior. Therefore, a simulation model of the bearing to predict the dynamic influence is essential. The presented model is a further step to develop an accurate and efficient characterization of the ball bearing’s rotor dynamic parameters such as stiffness and deflections as well as vibrational excitations induced by the discrete rolling elements. To make it applicable to high speed turbomachinery, the model considers centrifugal forces, gyroscopic effects and ball spinning. The consideration of an elastic outer ring makes the bearing model suitable for integrated lightweight bearing constructions used in modern aircraft turbines. In order to include transient rotordynamic behavior, the model is built as a full dynamic multibody simulation with time integration. To investigate the influence of the elasticity of the outer ring, a comparison with a rigid formulation for several rotational speeds and loads is presented.

  5. Vibrational Diver

    Science.gov (United States)

    Kozlov, Victor; Ivanova, Alevtina; Schipitsyn, Vitalii; Stambouli, Moncef

    2014-10-01

    The paper is concerned with dynamics of light solid in cavity with liquid subjected to rotational vibration in the external force field. New vibrational phenomenon - diving of a light cylinder to the cavity bottom is found. The experimental investigation of a horizontal annulus with a partition has shown that under vibration a light body situated in the upper part of the layer is displaced in a threshold manner some distance away from the boundary. In this case the body executes symmetric tangential oscillations. An increase of the vibration intensity leads to a tangential displacement of the body near the external boundary. This displacement is caused by the tangential component of the vibrational lift force, which appears as soon as the oscillations lose symmetry. In this case the trajectory of the body oscillatory motion has the form of a loop. The tangential lift force makes stable the position of the body on the inclined section of the layer and even in its lower part. A theoretical interpretation has been proposed, which explains stabilization of a quasi-equilibrium state of a light body near the cavity bottom in the framework of vibrational hydromechanics.

  6. Electric charge of a lightning ball

    Science.gov (United States)

    Grigor'ev, A. I.; Shiryaeva, S. O.; Petrushov, N. A.

    2016-09-01

    The electric charge of a lightning ball is found by comparing the electrohydrodynamic stabilities of a charged drop in an electrostatic suspension and a lightning ball floating in a superposition of the gravitational field and the surface electric field. It has been assumed that the electric field strength at the surface is limited by a breakdown value. For a lightning ball radius of 15 cm, its charge is estimated as several microcoulombs. Accordingly, the density of electrostatic energy accumulated in the lightning ball is on the order of one-hundredth of a joule per square centimeter. The density of the material that constitutes the lightning ball has been estimated for the case when the electric field strength at the site of its origination is several times higher than that in fine weather. The density of the lightning ball turns out to differ from that of air by only a few percents.

  7. Structural dynamic analysis of a ball joint

    Science.gov (United States)

    Hwang, Seok-Cheol; Lee, Kwon-Hee

    2012-11-01

    Ball joint is a rotating and swiveling element that is typically installed at the interface between two parts. In an automobile, the ball joint is the component that connects the control arms to the steering knuckle. The ball joint can also be installed in linkage systems for motion control applications. This paper describes the simulation strategy for a ball joint analysis, considering manufacturing process. Its manufacturing process can be divided into plugging and spinning. Then, the interested responses is selected as the stress distribution generated between its ball and bearing. In this paper, a commercial code of NX DAFUL using an implicit integration method is introduced to calculate the response. In addition, the gap analysis is performed to investigate the fitness, focusing on the response of the displacement of a ball stud. Also, the optimum design is suggested through case studies.

  8. Antiprotons and the Crystal Ball

    Energy Technology Data Exchange (ETDEWEB)

    Allgower, C.; Peaslee, D.

    1999-11-15

    During the 1998 running of the Crystal Ball experiment, a couple of brief test runs were done with the C6 beamline tuned to produce antiprotons. Specifically, one shift on July 29th produced runs 329-334 with the beam momentum set for 650 MeV/c, run 355 was done on July 31st with a 550 MeV/c beam momentum, and run 926-929 were obtained in a single shift on November 3rd, also with a beam momentum of 550 MeV/c. The beam tune for the November data was greatly superior to that of the July data, however. Therefore, only the November data have been analyzed in detail, and the results of this analysis are presented in this note. Due to the paucity of statistics that were obtained, it was decided not to attempt to publish the results. However, the results are valuable as a tool for planning a possible future program of dedicated measurements of antiproton-proton annihilation into all-neutral final states using the Crystal Ball. The data in fact show that the Crystal Ball with its large angular acceptance and multi-photon capability would be an excellent detector for such an experiment. Only one other such experiment (the Crystal Barrel experiment at CERN/LEAR) has ever been done in the past. Also in this document is a survey of published results for old antiproton-proton experiments, some discussion of physics issues that are relevant to measurements of {anti p} + p {r_arrow} all-neutral final states, and some estimates about the kinds of experiments they could contemplate doing in the C6 and D6 lines at the AGS.

  9. The Soccer-Ball Problem

    Science.gov (United States)

    Hossenfelder, Sabine

    2014-07-01

    The idea that Lorentz-symmetry in momentum space could be modified but still remain observer-independent has received quite some attention in the recent years. This modified Lorentz-symmetry, which has been argued to arise in Loop Quantum Gravity, is being used as a phenomenological model to test possibly observable effects of quantum gravity. The most pressing problem in these models is the treatment of multi-particle states, known as the 'soccer-ball problem'. This article briefly reviews the problem and the status of existing solution attempts.

  10. Improving Energy Efficiency Via Optimized Charge Motion and Slurry Flow in Plant Scale Sag Mills

    Energy Technology Data Exchange (ETDEWEB)

    Raj K. Rajamani; Jose Angel Delgadillo

    2006-07-21

    model calculations it was figured that the radial pulp lifter installed on the mill had less than optimum discharge capacity. A number of alternative designs were evaluated. The final choice was the Turbo Pulp Lifter for which Outukumpu Technology, Centennial, Colorado had filed a patent. After installation of the pulp lifter a 22% increase in throughput rate from 344 stph to 421 stph was realized. A 35% decrease in the SAG mill power draw from 3,908 HP to 2,526 HP (2,915 kW to 1,884 kW) was recorded. This equates to a 47% decrease in SAG unit energy consumption from 8.98 kWh/ton to 4.74 kWh/ton. A 11% decrease in SAG mill speed was observed indicating optimized ball strikes. Also, the ball chip generation from the SAG mill was reduced considerably. Further more, a 7% decrease in ball mill power draw from 4,843 HP to 4,491 HP (3,613 kW to 3,350 kW) was observed. This equates to a 24% decrease in ball mill unit energy consumption from 11.13 kWh/ton to 8.43 kWh/ton.

  11. Effect of milling on particle shape and surface energy heterogeneity of needle-shaped crystals.

    Science.gov (United States)

    Ho, Raimundo; Naderi, Majid; Heng, Jerry Y Y; Williams, Daryl R; Thielmann, Frank; Bouza, Peter; Keith, Adam R; Thiele, Greg; Burnett, Daniel J

    2012-10-01

    Milling and micronization of particles are routinely employed in the pharmaceutical industry to obtain small particles with desired particle size characteristics. The aim of this study is to demonstrate that particle shape is an important factor affecting the fracture mechanism in milling. Needle-shaped crystals of the β polymorph of D-mannitol were prepared from recrystallization in water. A portion of the recrystallized materials was ball-milled. Unmilled and milled sieved fractions of recrystallized D-mannitol were analyzed by dynamic image analysis (DIA) and inverse gas chromatography (IGC) at finite concentration to explain the breakage/fracture behavior. In the process of ball-milling, D-mannitol preferentially fractured along their shortest axis, exposing (011) plane with increased hydrophilicity and increased bounding rectangular aspect ratio. This is in contrary to attachment energy modeling which predicts a fracture mechanism across the (010) plane with increased hydrophobicity, and small change in particle shape. Crystal size, and more importantly, crystal shape and facet-specific mechanical properties, can dictate the fracture/cleavage behavior of organic crystalline materials. Thorough understanding of the crystal slip systems, combining attachment energy prediction with particle shape and surface characterization using DIA and IGC, are important in understanding fracture behavior of organic crystalline solids in milling and micronization.

  12. Investigating the controllable factors influencing the weight loss of grinding ball using SEM/EDX analysis and RSM model

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2015-06-01

    Full Text Available This study was aimed to investigate the effects of individual variables and their interactions on weight loss of grinding ball using the SEM/EDX analysis and RSM model. The results SEM/EDX analysis indicated that corrosion mechanism type for steel balls is pitting. In addition, abrasive corrosion was observed on high carbon chromium steel ball surface. It was also found that steel balls were formed from corrosion phases of Fe, O, S and Si. The results of RSM model showed that the linear effects of all factors and the quadratic effects of solid concentration and charge weight of balls were significant parameters on wear rate. Also, it was observed no interactions between factors. Furthermore, results indicated that degree of influence of factors on the wear rate was in the order of ball type > solid percentage > pH > solid percentage2 > charge weight2 > grinding time > rotation speed of mill > charge weight > throughout.

  13. Self-powered wireless vibration-sensing system for machining monitoring

    Science.gov (United States)

    Chung, Tien-Kan; Lee, Hao; Tseng, Chia-Yung; Lo, Wen-Tuan; Wang, Chieh-Min; Wang, Wen-Chin; Tu, Chi-Jen; Tasi, Pei-Yuan; Chang, Jui-Wen

    2013-04-01

    In this paper, we demonstrate an attachable energy-harvester-powered wireless vibration-sensing module for milling-process monitoring. The system consists of an electromagnetic energy harvester, MEMS accelerometer, and wireless module. The harvester consisting of an inductance and magnets utilizes the electromagnetic-induction approach to harvest the mechanical energy from the milling process and subsequently convert the mechanical energy to an electrical energy. Furthermore, through an energy-storage/rectification circuit, the harvested energy is capable of steadily powering both the accelerometer and wireless module. Through integrating the harvester, accelerometer, and wireless module, a self-powered wireless vibration-sensing system is achieved. The test result of the system monitoring the milling process shows the system successfully senses the vibration produced from the milling and subsequently transmits the vibration signals to the terminal computer. Through analyzing the vibration data received by the terminal computer, we establish a criterion for reconstructing the status, condition, and operating-sequence of the milling process. The reconstructed status precisely matches the real status of the milling process. That is, the system is capable of demonstrating a real-time monitoring of the milling process.

  14. Phenomenon of ball lightning and its outgrowths

    Energy Technology Data Exchange (ETDEWEB)

    Torchigin, V.P. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)]. E-mail: v_torchigin@mail.ru; Torchigin, A.V. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)

    2005-03-28

    New physical phenomena deduced from properties of ball lightning are considered under assumption that ball lightning is a light bubble comprising of a thin spherical layer of compressed air where an intense light circulates in all possible directions. Explanation of behavior of autonomous luminous objects produced at gas discharge is presented.

  15. Fusion characteristics of ball lighting like configurations

    Energy Technology Data Exchange (ETDEWEB)

    Sanduloviciu, M.; Lozneanu, E. [Universitatea A1. I. Cuza, Iasi (Romania)

    1997-12-31

    Assuming that an already proposed self-organization physical scenario is at the origin of both ball lightnings as well as fireballs produced in high intensity electrical discharges, we suggest a new possibility to create fusion relevant ball lightning like configurations in laboratory. Perhaps this becomes possible by prolonging in a controllable way their lifetime and energy content. (author)

  16. Soccer Ball Lift Coefficients via Trajectory Analysis

    Science.gov (United States)

    Goff, John Eric; Carre, Matt J.

    2010-01-01

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…

  17. The principal time balls of New Zealand

    Science.gov (United States)

    Kinns, Roger

    2017-04-01

    Accurate time signals in New Zealand were important for navigation in the Pacific. Time balls at Wellington and Lyttelton were noted in the 1880 Admiralty list of time signals, with later addition of Otago. The time ball service at Wellington started in March 1864 using the first official observatory in New Zealand, but there was no Wellington time ball service during a long period of waterfront redevelopment during the 1880s. The time ball service restarted in November 1888 at a different harbour location. The original mechanical apparatus was used with a new ball, but the system was destroyed by fire in March 1909 and was never replaced. Instead, a time light service was inaugurated in 1912. The service at Lyttelton, near Christchurch, began in December 1876 after construction of the signal station there. It used telegraph signals from Wellington to regulate the time ball. By the end of 1909, it was the only official time ball in New Zealand, providing a service that lasted until 1934. The Lyttelton time ball tower was an iconic landmark in New Zealand that had been carefully restored. Tragically, the tower collapsed in the 2011 earthquakes and aftershocks that devastated Christchurch. A daily time ball service at Port Chalmers, near Dunedin, started in June 1867, initially using local observatory facilities. The service appears to have been discontinued in October 1877, but was re-established in April 1882 as a weekly service, with control by telegraph from Wellington. The service had been withdrawn altogether by the end of 1909. Auckland never established a reliable time ball service, despite provision of a weekly service for mariners by a public-spirited citizen between August 1864 and June 1866. A time ball was finally installed on the Harbour Board building in 1901, but the signal was unreliable and it ceased in 1902. Complaints from ships' masters led to various proposals to re-establish a service. These concluded with erection of a time ball on the new

  18. Study of soccer ball flight trajectory

    Directory of Open Access Journals (Sweden)

    Javorova Juliana

    2018-01-01

    Full Text Available In this paper the trajectories of a soccer ball for the most important kicks in the football game - a corner kick and a direct free kick are studied. The soccer ball is modelled as an ideal rigid hollow spherical body with six degrees of freedom, which performs a general motion in an immovable air environment with constant parameters. The ball 3D orientation is determined by the three Cardan angles. The aerodynamic forces and moments with which the air environment acts to the ball are taken into account. Two of the most dangerous areas of the football goal are defined. Differential equations which describe the motion of the soccer ball are solved numerically by MatLab-Simulink.

  19. Dissolution Kinetics of Milled-Silicate Rock Fertilizers in Organic Acid

    Directory of Open Access Journals (Sweden)

    Joko Priyono

    2008-01-01

    Full Text Available A dissolution experiment was carried out to identify the effects of milling condition on dissolution kinetics of silicate rock fertilizers. Initially ground materials (Ø < 250 μm for basalt, dolerite, gneiss, and Ø < 150 μm for K-feldspar were further milled with a ball mill (Spex 8000 under dry and wet conditions for 10, 60, and 120 minutes. The rock powders were dissolved in a mixture of 0.01M acetic-citric acid at a rock powder/solvent ratio of 1/1000, and the solution was agitated continuously on a rotary shaker at 25o C. The concentrations of dissolved Na, K, Ca, Mg, Al, and Si from the milled rocks were determined at intervals from 1 hour up to 56 days. Results indicated that the relationships of quantity of dissolved rock and elemental plant nutrients (Et with time (t were well described by a power equation: Et = Eo + atn with reaction order (n of 0.3 – 0.8. Milling increased quantity of total and individual dissolved element (Et , dissolution rate (Rt, the proportion of rapidly soluble rock or element (Eo, and dissolution constant a. The increases in dissolution due to dry milling were larger than for wet milling. Although further proves should be provided, results of this dissolution experiment clearly indicates that SRFs may be used as multinutrient fertilizers as well as remedial materials for acidic soils; and dry milling may be applied as an appropriate method for manufacturing effective SRFs.

  20. Influence of Milling Conditions on the Hydriding Properties of Mg-C Nanocomposites

    Directory of Open Access Journals (Sweden)

    Hristina Stoyadinova

    2015-01-01

    Full Text Available Mg75 at.%, CB25 at.% (CB: carbon black composites were synthesized at different ball milling conditions (milling energy, milling duration, and environment and their hydriding properties were characterized by high-pressure DSC. The SEM observations revealed that the samples consist of 5–15 μm Mg particles, surrounded and in some cases coated by carbon particles. X-ray diffraction analysis showed that the Mg phase of all as-obtained composite powders is nanocrystalline with average crystallite size in the range 20–30 nm, depending on the milling conditions. The best hydriding properties, expressed in low-temperature hydriding (below 150°C and improved cycle life, showed the composites milled at dry conditions. This is obviously due mainly to the successful Mg surface protection by the carbon. Additional decrease of the hydriding temperature (<100°C was achieved applying higher-energy milling, but at the same time the cycling stability deteriorated, due to the extremely fine particles and microstructure achieved under these conditions. The composites milled in the presence of heptane showed rapid capacity decline during cycling as well. The observed difference in the hydriding behavior of the Mg-CB composites is attributed to the different coating efficiency of the carbon milled under different conditions with Mg, which is supposed to protect magnesium from oxidation and plays a catalytic role for the hydriding reaction.

  1. Effect of milling time on microstructure and mechanical properties of Cu–Ni–graphite composites

    Science.gov (United States)

    Wang, Yiran; Gao, Yimin; Li, Yefei; Zhang, Chao; Huang, Xiaoyu; Zhai, Wenyan

    2017-09-01

    Cu–Ni–graphite composites are intended for application in switch slide baseplate materials. The microstructure of the composites depends strongly on the ball milling time, and a suitable time can significantly improve the properties of the Cu–Ni–graphite composites. In this study, a two-step milling method was employed. The morphology evolution and microstructural features of the powder was characterized at different milling times. Afterwards, the Cu–Ni–graphite composites were prepared in the process of cold pressing, sintering, re-pressing and re-sintering as a function of the different milling times. Finally, both the microstructure and mechanical properties of the Cu–Ni–graphite composites are discussed. The results show that no new phase was generated during the milling process. The morphology evolution of the mixture of Cu/Ni powder changed from spherical-like to cubic-like, plate-like and flake-like with an increasing milling time. The microstructure of the composites consisted of α-phase and graphite. The boundary area and quantity of pores changed as the milling time increased. The relative density, hardness and flexural strength reached maximum values at 15 h of milling time.

  2. La balle et la plume

    Directory of Open Access Journals (Sweden)

    Peter Marquis

    2012-06-01

    Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  3. Vibrating minds

    CERN Document Server

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  4. High energy milling of alumina synthesized by combustion reaction using attritor mill vertical axis: influence of rotation speed; Moagem de alta energia de alumina sintetizada por reacao de combustao utilizando moinho atritor de eixo vertical: influencia da velocidade de rotacao

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.C. da; Silva, F.N.; Costa, A.C.F.M. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Costa, G.B. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Producao; Freitas, N.L. de, E-mail: normanda@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Tecnologia do Desenvolvimento

    2014-07-01

    The use of a reactive high energy milling for the synthesis of ceramic powders of metal oxides, carbides, borides, nitrides or mixtures of ceramics or ceramic and metal compounds have been widely reported. The objective of this study is to assess how high energy ball milling (not reactive) using different rotations, 300, 400 and 500 rpm, alter the structure and morphology of alpha-alumina powders synthesized by combustion reaction. Time and temperature of the combustion reaction has been reported for the synthesis of aluminas. The samples of unmilled and milled alumina were characterized by XRD, SEM and particle size analysis. The results showed that the maximum reaction temperature reached was 598°C. The variation of the rotation of the mill did not affect the majority alpha-Al2O3 by stable crystal phase all samples. The median particle diameter of the milled samples at different speeds decreased with respect to unground sample. (author)

  5. BALL - biochemical algorithms library 1.3

    Directory of Open Access Journals (Sweden)

    Stöckel Daniel

    2010-10-01

    Full Text Available Abstract Background The Biochemical Algorithms Library (BALL is a comprehensive rapid application development framework for structural bioinformatics. It provides an extensive C++ class library of data structures and algorithms for molecular modeling and structural bioinformatics. Using BALL as a programming toolbox does not only allow to greatly reduce application development times but also helps in ensuring stability and correctness by avoiding the error-prone reimplementation of complex algorithms and replacing them with calls into the library that has been well-tested by a large number of developers. In the ten years since its original publication, BALL has seen a substantial increase in functionality and numerous other improvements. Results Here, we discuss BALL's current functionality and highlight the key additions and improvements: support for additional file formats, molecular edit-functionality, new molecular mechanics force fields, novel energy minimization techniques, docking algorithms, and support for cheminformatics. Conclusions BALL is available for all major operating systems, including Linux, Windows, and MacOS X. It is available free of charge under the Lesser GNU Public License (LPGL. Parts of the code are distributed under the GNU Public License (GPL. BALL is available as source code and binary packages from the project web site at http://www.ball-project.org. Recently, it has been accepted into the debian project; integration into further distributions is currently pursued.

  6. Comminution of B4C powders with a high-energy mill operated in air in dry or wet conditions and its effect on their spark-plasma sinterability

    DEFF Research Database (Denmark)

    Ortiz, Angel L.; Sánchez-Bajo, Florentino; Leal, Victor Manuel Candelario

    2017-01-01

    The comminution of a typical submicrometre B4C powder with a high-energy mill (i.e., a shaker mill) operated in air in either a dry or a wet environment was investigated. It was found that dry shaker milling (i.e., high-energy ball-milling) is able to progressively refine the B4C particles...... found that both dry and wet milling modify the B4C crystal structure, attributable to carbon enrichment. Consequently, dry shaker milling was found to be more recommendable than wet shaker milling to provide B4C starting powders with superior sinterability. A comparative densification study by spark......-plasma sintering confirmed this recommendation, and also showed the usefulness of dry shaker milling to obtain refined B4C microstructures for structural applications....

  7. Effects of milling time on the development of porosity in Cu by the reduction of CuO

    Directory of Open Access Journals (Sweden)

    Laura N. Guevara

    2017-08-01

    Full Text Available Microscale and nanoscale CuO was dispersed in Cu using room temperature high-energy ball milling over time intervals of 5, 30, 60, 120, and 240 min. These samples were then annealed under a reducing atmosphere for 1 h at temperatures of 400, 600, 800 and 1000 °C to create porosity by the reduction of the entrained oxides. Increases in porosity exceeding 40% were achieved using intermediate milling times and annealing temperatures. When considered cumulatively, the most effective processing conditions were a milling time of 30 min and expansion at 800 °C, but variations exist within each sample type. The complex relationship between milling time and annealing temperature is investigated in terms of particle size, morphology and microstructure. The findings indicate that room temperature milling is more efficient at producing porosity than comparable cryogenic methods, and this may enable industrial scaling of the process.

  8. Milling solid proteins to enhance activity after melt-encapsulation.

    Science.gov (United States)

    Lee, Parker W; Maia, João; Pokorski, Jonathan K

    2017-11-25

    Polymeric systems for the immobilization and delivery of proteins have been extensively used for therapeutic and catalytic applications. While most devices have been created via solution based methods, hot melt extrusion (HME) has emerged as an alternative due to the high encapsulation efficiencies and solvent-free nature of the process. HME requires high temperatures and mechanical stresses that can result in protein aggregation and denaturation, but additives and chemical modifications have been explored to mitigate these effects. This study explores the use of solid-state ball milling to decrease protein particle size before encapsulation within poly(lactic-co-glycolic acid) (PLGA) via HME. The impact of milling on particle dispersion, retained enzymatic activity, secondary structure stability, and release was explored for lysozyme, glucose oxidase, and the virus-like particle derived from Qβ to fully understand the impact of milling on protein systems with different sizes and complexities. The results of this study describe the utility of milling to further increase the stability of protein/polymer systems prepared via HME. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Characterization of Tool Wear in High-Speed Milling of Hardened Powder Metallurgical Steels

    Directory of Open Access Journals (Sweden)

    Fritz Klocke

    2011-01-01

    Full Text Available In this experimental study, the cutting performance of ball-end mills in high-speed dry-hard milling of powder metallurgical steels was investigated. The cutting performance of the milling tools was mainly evaluated in terms of cutting length, tool wear, and cutting forces. Two different types of hardened steels were machined, the cold working steel HS 4-2-4 PM (K490 Microclean/66 HRC and the high speed steel HS 6-5-3 PM (S790 Microclean/64 HRC. The milling tests were performed at effective cutting speeds of 225, 300, and 400 m/min with a four fluted solid carbide ball-end mill (0 = 6, TiAlN coating. It was observed that by means of analytically optimised chipping parameters and increased cutting speed, the tool life can be drastically enhanced. Further, in machining the harder material HS 4-2-4 PM, the tool life is up to three times in regard to the less harder material HS 6-5-3 PM. Thus, it can be assumed that not only the hardness of the material to be machined plays a vital role for the high-speed dry-hard cutting performance, but also the microstructure and thermal characteristics of the investigated powder metallurgical steels in their hardened state.

  10. Process parameter dependent growth phenomena of naproxen nanosuspension manufactured by wet media milling.

    Science.gov (United States)

    Bitterlich, A; Laabs, C; Krautstrunk, I; Dengler, M; Juhnke, M; Grandeury, A; Bunjes, H; Kwade, A

    2015-05-01

    The production of nanosuspensions has proved to be an effective method for overcoming bioavailability challenges of poorly water soluble drugs. Wet milling in stirred media mills and planetary ball mills has become an established top-down-method for producing such drug nanosuspensions. The quality of the resulting nanosuspension is determined by the stability against agglomeration on the one hand, and the process parameters of the mill on the other hand. In order to understand the occurring dependencies, a detailed screening study, not only on adequate stabilizers, but also on their optimum concentration was carried out for the active pharmaceutical ingredient (API) naproxen in a planetary ball mill. The type and concentration of the stabilizer had a pronounced influence on the minimum particle size obtained. With the best formulation the influence of the relevant process parameters on product quality was investigated to determine the grinding limit of naproxen. Besides the well known phenomenon of particle agglomeration, actual naproxen crystal growth and morphology alterations occurred during the process which has not been observed before. It was shown that, by adjusting the process parameters, those effects could be reduced or eliminated. Thus, besides real grinding and agglomeration a process parameter dependent ripening of the naproxen particles was identified to be a concurrent effect during the naproxen fine grinding process. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Release Control of Dye from Agar Ball

    OpenAIRE

    板屋, 智之; 山村, 俊貴; 唐澤, 有太朗

    2013-01-01

    Agar is a special product of Nagano prefecture. To utilize agar gel as adsorbing or releasing material of dyes or drugs, spherical agar gel “agar ball” was prepared by dropping aqueous agar solution into salad oil. And releasing behavior of a dye (rhodamine B) from agar ball was studied. The dye is released easily from agar ball, but the release can be controlled by hybiridazation of agar and galatin. In addition, it was found that agar ball could extract the dye from oil phase containing the...

  12. IMPROVING ENERGY EFFICIENCY VIA OPTIMIZED CHARGE MOTION AND SLURRY FLOW IN PLANT SCALE SAG MILLS

    Energy Technology Data Exchange (ETDEWEB)

    Raj K. Rajamani; Sanjeeva Latchireddi; Sravan K. Prathy; Trilokyanath Patra

    2005-12-01

    The U.S. mining industry operates approximately 80 semi-autogenesis grinding mills (SAG) throughout the United States. Depending on the mill size the SAG mills draws between 2 MW and 17 MW. The product from the SAG mill is further reduced in size using pebble crushers and ball mills. Hence, typical gold or copper ore requires between 2.0 and 7.5 kWh per ton of energy to reduce the particle size. Considering a typical mining operation processes 10,000 to 100,000 tons per day the energy expenditure in grinding is 50 percent of the cost of production of the metal. A research team from the University of Utah is working to make inroads into saving energy in these SAG mills. In 2003, Industries of the Future Program of the Department of Energy tasked the University of Utah team to build a partnership between the University and the mining industry for the specific purpose of reducing energy consumption in SAG mills. A partnership was formed with Cortez Gold Mines, Kennecott Utah Copper Corporation, Process Engineering Resources Inc. and others. In the current project, Cortez Gold Mines played a key role in facilitating the 26-ft SAG mill at Cortez as a test mill for this study. According to plant personnel, there were a number of unscheduled shut downs to repair broken liners and the mill throughput fluctuated depending on ore type. The University team had two softwares, Millsoft and FlowMod to tackle the problem. Millsoft is capable of simulating the motion of charge in the mill. FlowMod calculates the slurry flow through the grate and pulp lifters. Based on this data the two models were fine-tuned to fit the Cortez SAG will. In the summer of 2004 a new design of shell lifters were presented to Cortez and in September 2004 these lifters were installed in the SAG mill. By December 2004 Cortez Mines realized that the SAG mill is drawing approximately 236-kW less power than before while maintaining the same level of production. In the first month there was extreme cycling

  13. Effect of milling temperature and post-milling cooling procedures on rice milling quality appraisals

    Science.gov (United States)

    The objective of this research was to study the effects of different milling conditions and post-milling handling procedures on appraised milling quality of rough rice. Samples of medium grain rough rice (M202) with moisture content (MC) of 11.5±0.2% were used for this study. To create different mil...

  14. Production of Ball-Lightning-Like Luminous Balls by Electrical Discharges in Silicon

    Science.gov (United States)

    Paiva, Gerson Silva; Pavão, Antonio Carlos; Alpes de Vasconcelos, Elder; Mendes, Odim, Jr.; Felisberto da Silva, Eronides, Jr.

    2007-01-01

    We performed electric arc discharges in pure Si to generate luminous balls with lifetime in the order of seconds and several properties usually reported for natural ball lightning. This simple experiment does not rely on energy sources and excitation mechanisms that are improbable in the natural phenomenon and clearly demonstrates the role of vaporization and oxidation of Si, as proposed by the Abrahamson-Dinniss theory for ball-lightning formation.

  15. Production of ball-lightning-like luminous balls by electrical discharges in silicon.

    Science.gov (United States)

    Paiva, Gerson Silva; Pavão, Antonio Carlos; Alpes de Vasconcelos, Elder; Mendes, Odim; da Silva, Eronides Felisberto

    2007-01-26

    We performed electric arc discharges in pure Si to generate luminous balls with lifetime in the order of seconds and several properties usually reported for natural ball lightning. This simple experiment does not rely on energy sources and excitation mechanisms that are improbable in the natural phenomenon and clearly demonstrates the role of vaporization and oxidation of Si, as proposed by the Abrahamson-Dinniss theory for ball-lightning formation.

  16. The ball SITE sign: Ball sports-induced targetoid erythema in a racquetball player.

    Science.gov (United States)

    Cohen, Philip R

    2015-07-01

    Cutaneous injury following impact of a high velocity ball to the skin may result in either erythema or purpura or both. The lesion typically appears as an annular ring of erythema with or without accompanying ecchymosis when the skin is contacted by a paintball, a ping pong ball, a racquetball or a squash ball. To describe a girl with targetoid erythema following impact of a racquetball on her flank and back and to review other sports associated with this response to skin injury. PubMed was used to search the following terms, separately and in combination: ball, erythema, paint, ping pong, purpura, racquetball, sign, site, sports, squash, targetoid. All papers were reviewed and relevant manuscripts, along with their reference citations, were evaluated. A 13-year-old girl developed an annular red ring surrounding a central area of normal appearing skin on her right flank and upper back where a racquetball traveling at a high velocity contacted her skin. Similar appearing lesions of targetoid erythema have been described at the cutaneous impact sites of either paintballs, ping pong balls, squash balls; in addition to erythema, purpura may also concurrently appear or subsequently develop at the contact location of the ball with the skin. Targetoid erythema is a pathognomonic cutaneous presentation resulting from the impact of either a paintball, ping pong ball, racquetball or squash ball-that is traveling at a high velocity-with a sport participant's skin. The ball SITE (sports-induced targetoid erythema) sign is suggested as a unifying nomenclature to designate this unique, ball sport-associated, cutaneous dermatosis in athletes participating in sports in which high velocity impact of the ball with the skin may occur.

  17. Opto-mechanical interactions in split ball resonators (Presentation Recording)

    Science.gov (United States)

    Sun, Yue; Suchkov, Sergey V.; Miroshnichenko, Andrey E.; Sukhorukov, Andrey A.

    2015-09-01

    We demonstrate that a gold split-ball resonator (SBR) in the form of a spherical nanoparticle with a cut supports both optical magnetic and acoustic modes, which have strong field confinement around the cut. Such localization away from the bottom is expected to lead to an immunity to anchor loss and thus potentially high quality factors of acoustic oscillations when positioned on a substrate. As a result, when a planewave pulse excites the optical resonance, it can then efficiently drive the acoustic vibration through laser heating and/or optical forces. We estimate the overall heat variation by modelling the optical energy dissipation inside the SBR due to the dispersive and absorbing nature of gold at optical wavelengths. The optically induced force is given by the time averaged Lorentz force density. We simulate the mechanical vibrations under the optical excitation through time-dependent simulations using solid mechanics module of COMSOL software. Assuming a moderate quality factor of 10, under a plane wave pulsed laser pump which gives 100K temperature change to the SBR, both the laser heating and optical forces lead to the excitation of the acoustic mode at the same frequency with different magnitudes of 200pm and 10pm, resulting 10% and 0.5% modification of the total optical scattering, respectively. These results show that the SBRs support strong opto-mechanical coupling and are promising in applications such as surface-enhanced Raman spectroscopy and detection of localised strain.

  18. Energy transfer problems of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egely, G.

    1986-04-01

    The paper analyzes the energy transport phenomenon of ball lightnings, but momentum and charge transport phenomena are considered as well. The physical properties as energy density and transfer are investigated using several observers' accounts of interactions with different objects. It is shown that contrary to previous assumptions the ball lightning has negative electric charge, and very high internal energy density. Both internal and external energy source models are analyzed, and it is shown that regardless to the details of a given model neither of them can explain actual observations. This has been validated by a well documented case study, and by several additional observations. An entirely new, testable model is suggested, which is able to stand for all observed properties of ball lightnings, and it explains the cause of rarity of ball lightnings, and the reasons of the unsuccessful experimental efforts. It is shown that the plasma sphere is just a visible side effect of a more important phenomenon.

  19. Static Load Distribution in Ball Bearings

    Science.gov (United States)

    Ricci, Mario

    2010-01-01

    A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.

  20. How Magnus Bends the Flying Ball--Experimenting and Modeling

    Science.gov (United States)

    Timková, V.; Ješková, Z.

    2017-01-01

    Students are well aware of the effect of the deflection of sports balls when they have been given a spin. A volleyball, tennis, or table tennis ball served with topspin results in an additional downward force that makes the ball difficult to catch and return. In soccer, the effect of sidespin causes the ball to curve unexpectedly sideways,…

  1. Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

    Science.gov (United States)

    Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

    2013-09-01

    We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025). Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Rotating Boson Stars and Q-Balls

    OpenAIRE

    Kleihaus, Burkhard; Kunz, Jutta; List, Meike

    2005-01-01

    We consider axially symmetric, rotating boson stars. Their flat space limits represent spinning Q-balls. We discuss their properties and determine their domain of existence. Q-balls and boson stars are stationary solutions and exist only in a limited frequency range. The coupling to gravity gives rise to a spiral-like frequency dependence of the boson stars. We address the flat space limit and the limit of strong gravitational coupling. For comparison we also determine the properties of spher...

  3. Energy-Saving Vibration Impulse Coal Degradation at Finely Dispersed Coal-Water Slurry Preparation

    Directory of Open Access Journals (Sweden)

    Moiseev V.A.

    2015-01-01

    Full Text Available Theoretical and experimental research results of processes of finely dispersed coal-water slurry preparation for further generation of energetic gas in direct flow and vortex gas generator plants have been presented. It has been stated that frequency parameters of parabolic vibration impulse mill influence degradation degree. Pressure influence on coal parameters in grinding cavity has been proven. Experimental researches have proven efficiency of vibration impulse mill with unbalanced mass vibrator generator development. Conditions of development on intergranular walls of coal cracks have been defined.

  4. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

      lab   studies   in   that   we   found   a   decreased   detection   rate   in   busy   environments.   Here   we   test   with   a   much   larger   sample   and   age   range,   and   contribute   with   the   first   vibration  sensitivity  testing  outside  the  lab  in  an  urban   public...

  5. High resolution Transmission Electron Microscopy characterization of a milled oxide dispersion strengthened steel powder

    Energy Technology Data Exchange (ETDEWEB)

    Loyer-Prost, M., E-mail: marie.loyer-prost@cea.fr [DEN-Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Merot, J.-S. [Laboratoire d’Etudes des Microstructures – UMR 104, CNRS/ONERA, BP72-29, Avenue de la Division Leclerc, 92 322, Châtillon (France); Ribis, J. [DEN-Service de Recherches de Métallurgie Appliquée, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Le Bouar, Y. [Laboratoire d’Etudes des Microstructures – UMR 104, CNRS/ONERA, BP72-29, Avenue de la Division Leclerc, 92 322, Châtillon (France); Chaffron, L. [DEN-Service de Recherches de Métallurgie Appliquée, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Legendre, F. [DEN-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France)

    2016-10-15

    Oxide Dispersion Strengthened (ODS) steels are promising materials for generation IV fuel claddings as their dense nano-oxide dispersion provides good creep and irradiation resistance. Even if they have been studied for years, the formation mechanism of these nano-oxides is still unclear. Here we report for the first time a High Resolution Transmission Electron Microscopy and Energy Filtered Transmission Electron Microscopy characterization of an ODS milled powder. It provides clear evidence of the presence of small crystalline nanoclusters (NCs) enriched in titanium directly after milling. Small NCs (<5 nm) have a crystalline structure and seem partly coherent with the matrix. They have an interplanar spacing close to the (011) {sub bcc} iron structure. They coexist with larger crystalline spherical precipitates of 15–20 nm in size. Their crystalline structure may be metastable as they are not consistent with any Y-Ti-O or Ti-O structure. Such detailed observations in the as-milled grain powder confirm a mechanism of Y, Ti, O dissolution in the ferritic matrix followed by a NC precipitation during the mechanical alloying process of ODS materials. - Highlights: • We observed an ODS ball-milled powder by high resolution transmission microscopy. • The ODS ball-milled powder exhibits a lamellar microstructure. • Small crystalline nanoclusters were detected in the milled ODS powder. • The nanoclusters in the ODS milled powder are enriched in titanium. • Larger NCs of 15–20 nm in size are, at least, partly coherent with the matrix.

  6. Secret of a ball lightning

    OpenAIRE

    Савич, Эдуард Владимирович

    2013-01-01

    Шаровая молния – явление природы, происходящее при ударе линейной молнии с ее воздействием тепловой и магнитной энергии, возникающей вокруг канала линейной молнии и в результате образующей из окружающего воздуха облако пара, переходящего под воздействием магнитного поля сегнетоэлектрическое состояние. A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming...

  7. The effect of calcination on reactive milling of anthracite as potential precursor for graphite production

    Energy Technology Data Exchange (ETDEWEB)

    Burgess-Clifford, Caroline E.; Van Essendelft, Dirk T. [The EMS Energy Institute, C211 Coal Utilization Laboratory, Penn State University, University Park, PA 16802 (United States); Narayanan, Deepa L. [Puget Sound Energy, 10885 NE 4th PSE-09S, Bellevue, WA 98004 (United States); Jain, Puja; Lueking, Angela D. [Department of Energy and Mineral Engineering, Pennsylvania State University, 120 Hosler, University Park, PA 16802 (United States); Sakti, Apurba [School of Earth Atmospheric and Environmental Sciences, University of Manchester, Manchester (United Kingdom)

    2009-12-15

    The effect of a pretreatment using reactive ball milling and calcination on the graphitizability of an anthracite coal is explored. A thermal anneal of Buck Mountain anthracite at 1400 C in argon increased the L{sub c} crystallite dimension (from 12 to 20 A) and led to an increase in the oxidation temperature of the product. Ball milling of the coal reduced particle size with a nominal effect on carbon order and the degree of graphitization after the 1400 C thermal anneal (L{sub c} from 18 to 29 A). Ball milling in cyclohexene led to a substantial increase in the graphitizability at 1400 C (L{sub c} from 12 to 50 A). The enhanced reactivity was due to both carbon structure and introduced metal. The products of the mechano-chemical pretreatment and thermal anneal consisted of nanographene ribbons and multi-walled nanopolyhedral particles. It oxidized at moderate temperatures and had a high (74.3%) degree of graphitization based on X-ray diffraction analysis; the derived material has potential as filler for production of graphite. (author)

  8. Estimatation of talc properties after milling

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sublania Harish, E-mail: hitu.sublania4@gmail.com [Govt.College, Nohar(Hanumangarh) Rajasthan (India); Singh, K.J. [Govt College, Suratgarh(Sriganganagar) Rajasthan (India); Somani, A.K. [Govt. Polytechnic College, Hanumangarh, Rajasthan (India)

    2016-05-06

    As we know Talc is a natural mineral which is used in different areas for different purposes. The principle of this paper is analysis of structural properties of the natural talc therefore the different types of structural treatments were used. Talc powder was dry milled by vibration. Then the samples were alkalized by hydrochloric acid. To study its structural property the specific surface area and cumulative pore volume values of the starting material were 10.1 m{sup 2}/g and 0.09 cm{sup 3}/g. It was observed that the acid treatments were main reason to increase of the specific surface area. A small increment in the V{sub cp} was observed for all prepared samples. The treated samples were examined by using X-ray diffraction techniques.

  9. Aerodynamic drag of modern soccer balls.

    Science.gov (United States)

    Asai, Takeshi; Seo, Kazuya

    2013-12-01

    Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through a wind tunnel test and ball trajectory simulations, this study shows that the aerodynamic resistance of the new 32-panel soccer ball is larger in the high-speed region and lower in the middle-speed region than that of the previous 14- and 8-panel balls. The critical Reynolds number of the Roteiro, Teamgeist II, Jabulani, and Tango 12 was ~2.2 × 10(5) (drag coefficient, C d  ≈ 0.12), ~2.8 × 10(5) (C d  ≈ 0.13), ~3.3 × 10(5) (C d  ≈ 0.13), and ~2.4 × 10(5) (C d  ≈ 0.15), respectively. The flight trajectory simulation suggested that the Tango 12, one of the newest soccer balls, has less air resistance in the medium-speed region than the Jabulani and can thus easily acquire large initial velocity in this region. It is considered that the critical Reynolds number of a soccer ball, as considered within the scope of this experiment, depends on the extended total distance of the panel bonds rather than the small designs on the panel surfaces.

  10. Effect of a ball skill intervention on children's ball skills and cognitive functions

    NARCIS (Netherlands)

    Westendorp-Haverdings, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

    Purpose: This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning

  11. Keeping Your Eyes Continuously on the Ball While Running for Catchable and Uncatchable Fly Balls

    NARCIS (Netherlands)

    Postma, Dees B. W.; den Otter, A. Rob; Zaal, Frank T. J. M.

    2014-01-01

    When faced with a fly ball approaching along the sagittal plane, fielders need information for the control of their running to the interception location. This information could be available in the initial part of the ball trajectory, such that the interception location can be predicted from its

  12. Research on Degeneration Model of Neural Network for Deep Groove Ball Bearing Based on Feature Fusion

    Directory of Open Access Journals (Sweden)

    Lijun Zhang

    2018-02-01

    Full Text Available Aiming at the pitting fault of deep groove ball bearing during service, this paper uses the vibration signal of five different states of deep groove ball bearing and extracts the relevant features, then uses a neural network to model the degradation for identifying and classifying the fault type. By comparing the effects of training samples with different capacities through performance indexes such as the accuracy and convergence speed, it is proven that an increase in the sample size can improve the performance of the model. Based on the polynomial fitting principle and Pearson correlation coefficient, fusion features based on the skewness index are proposed, and the performance improvement of the model after incorporating the fusion features is also validated. A comparison of the performance of the support vector machine (SVM model and the neural network model on this dataset is given. The research shows that neural networks have more potential for complex and high-volume datasets.

  13. Application of Silicon Nitride (Si3N4 Ceramics in Ball Bearing

    Directory of Open Access Journals (Sweden)

    Wijianto Wijianto

    2016-08-01

    operation up to 1000°C, greater thermal shock resistance, lower density and low thermal expansion. This properties gives some benefit for ball bearing material such as higher running speed, reduce vibration of the shaft, will improve the life time and maintenance cost, lower heat generated, less energy consumption, lower wear rate, reducing noise level and reduce of using lubricant. The sintering methods are used to produce ball bearing from silicon nitride. Some techniques can be applied to increase ceramics strength which are reduce porosity, reduce grain size, reduce surface flaw and proof stressing. The surface finishing of the ceramic bearing is very important because silicon nitride as a brittle material, its strength is limited to the flaw sizes especially the flaw at the surface.

  14. Assessment of crystalline disorder in cryo-milled samples of indomethacin using atomic pair-wise distribution functions.

    Science.gov (United States)

    Bøtker, Johan P; Karmwar, Pranav; Strachan, Clare J; Cornett, Claus; Tian, Fang; Zujovic, Zoran; Rantanen, Jukka; Rades, Thomas

    2011-09-30

    The aim of this study was to investigate the usefulness of the atomic pair-wise distribution function (PDF) to detect the extension of disorder/amorphousness induced into a crystalline drug using a cryo-milling technique, and to determine the optimal milling times to achieve amorphisation. The PDF analysis was performed on samples of indomethacin obtained by cryogenic ball milling (cryo-milling) for different periods of time. X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), polarised light microscopy (PLM) and solid state nuclear magnetic resonances (ss-NMR) were also used to analyse the cryo-milled samples. The high similarity between the γ-indomethacin cryogenic ball milled samples and the crude γ-indomethacin indicated that milled samples retained residual order of the γ-form. The PDF analysis encompassed the capability of achieving a correlation with the physical properties determined from DSC, ss-NMR and stability experiments. Multivariate data analysis (MVDA) was used to visualize the differences in the PDF and XRPD data. The MVDA approach revealed that PDF is more efficient in assessing the introduced degree of disorder in γ-indomethacin after cryo-milling than MVDA of the corresponding XRPD diffractograms. The PDF analysis was able to determine the optimal cryo-milling time that facilitated the highest degree of disorder in the samples. Therefore, it is concluded that the PDF technique may be used as a complementary tool to other solid state methods and that further investigations are warranted to elucidate the capabilities of this technique. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Note: A SMA wire actuated extremely long-lifetime release actuator using two ball-lock mechanisms

    Science.gov (United States)

    Huang, Dawei; Yan, Xiaojun; Zhang, Xiaoyong; Bai, Haibo; Wang, Xian; Liu, Ying

    2017-05-01

    A shape memory alloy (SMA)-wire actuated release actuator with an extremely long lifetime was designed and validated. To ensure the ability of repeated actuation, two stages of ball-lock mechanisms were adopted to reduce the load in the SMA wire. In addition, a length-increasing design of the SMA wire was employed. Validation tests, including function tests, vibration tests, shock tests, and thermal vacuum tests were conducted on prototypes. According to the test results, the actuator can release a maximum preload of 15 kN and has a lifetime of more than 693 cycles. Furthermore, the actuator can function well, even under severe thermal and vibration environments.

  16. Effect of a ball skill intervention on children's ball skills and cognitive functions.

    Science.gov (United States)

    Westendorp, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

    2014-02-01

    This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning disorders. Ninety-one children with learning disorders (age 7-11 yr old) were recruited from six classes in a Dutch special-needs primary school. The six classes were assigned randomly either to the intervention or to the control group. The control group received the school's regular physical education lessons. In the intervention group, ball skills were practiced in relative static, simple settings as well as in more dynamic and cognitive demanding settings. Both groups received two 40-min lessons per week. Children's scores on the Test of Gross Motor Development-2 (ball skills), Tower of London (problem solving), Trail Making Test (cognitive flexibility), Dutch Analysis of Individual Word Forms (reading), and the Dutch World in Numbers test (mathematics) at pretest, posttest, and retention test were used to examine intervention effects. The results showed that the intervention group significantly improved their ball skills, whereas the control group did not. No intervention effects were found on the cognitive parameters. However, within the intervention group, a positive relationship (r = 0.41, P = 0.007) was found between the change in ball skill performance and the change in problem solving: the larger children's improvement in ball skills, the larger their improvement in problem solving. The present ball skill intervention is an effective instrument to improve the ball skills of children with learning disorders. Further research is needed to examine the effect of the ball skill intervention on the cognitive parameters in this population.

  17. Laser Sintering Technology and Balling Phenomenon.

    Science.gov (United States)

    Oyar, Perihan

    2017-10-13

    The aim of this review was to evaluate the balling phenomenon which occurs typically in Selective Laser Sintering (SLS). The balling phenomenon is a typical SLS defect, and observed in laser sintered powder, significantly reduces the quality of SLS, and hinders the further development of SLS Technology. Electronic database searches were performed using Google Scholar. The keywords "laser sintering, selective laser sintering, direct metal laser melting, and balling phenomenon" were searched in title/abstract of publications, limited to December 31, 2016. The inclusion criteria were SLS, balling phenomenon, some alloys (such as Cr-Co, iron, stainless steel, and Cu-based alloys) mechanical properties, microstructure and bond strength between metal-ceramic crown, laboratory studies, full text, and in English language. A total of 100 articles were found the initial search and yielded a total of 50 studies, 30 of which did not fulfill the inclusion criteria and were therefore excluded. In addition, 20 studies were found by screening the reference list of all included publications. Finally, 40 studies were selected for this review. The method in question is regulated by powder material characteristics and the conditions of laser processing. The procedure of formation, affecting factors, and the mechanism of the balling effect are very complex.

  18. Model-based Process Monitoring and Control of Micro-milling using Active Magnetic Bearings

    NARCIS (Netherlands)

    Blom, R.S.

    2011-01-01

    The process of micro-milling is a promising technology for the fabrication of micro-parts with arbitrary 3D features in a wide range of materials. However, as a result of the reduced dimensions, the susceptibility of the process for machine tool errors and vibrations is higher, having adverse

  19. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  20. Linaria repens (L.) Mill. x L. vulgaris Mill

    NARCIS (Netherlands)

    Ooststroom, van S.J.; Reichgelt, Th.J.

    1958-01-01

    Linaria repens (L.) Mill. (L. monspessulana (L.) Mill.; L. striata Lamk. & DC.) is bij ons reeds meermalen als adventief gevonden en blijkt zich op enkele plaatsen te handhaven. Dit laatste is bv. het geval te Arnhem, aan de Koningsweg. De soort werd daar in 1952 aangetroffen door Dr. A.G. de Wilde

  1. Optimization of chemical composition in the manufacturing process of flotation balls based on intelligent soft sensing

    Directory of Open Access Journals (Sweden)

    Dučić Nedeljko

    2016-01-01

    Full Text Available This paper presents an application of computational intelligence in modeling and optimization of parameters of two related production processes - ore flotation and production of balls for ore flotation. It is proposed that desired chemical composition of flotation balls (Mn=0.69%; Cr=2.247%; C=3.79%; Si=0.5%, which ensures minimum wear rate (0.47 g/kg during copper milling is determined by combining artificial neural network (ANN and genetic algorithm (GA. Based on the results provided by neuro-genetic combination, a second neural network was derived as an ‘intelligent soft sensor’ in the process of white cast iron production. The proposed ANN 12-16-12-4 model demonstrated favourable prediction capacity, and can be recommended as a ‘intelligent soft sensor’ in the alloying process intended for obtaining favourable chemical composition of white cast iron for production of flotation balls. In the development of intelligent soft sensor data from the two real production processes was used. [Projekat Ministarstva nauke Republike Srbije, br. TR35037 i br. TR35015

  2. Electrostatic charge bounds for ball lightning models

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Karl D [Department of Technology, Texas State University, San Marcos, TX 78666 (United States)], E-mail: kdstephan@txstate.edu

    2008-03-15

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings.

  3. Electrostatic charge bounds for ball lightning models

    Science.gov (United States)

    Stephan, Karl D.

    2008-03-01

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings.

  4. Relativistic-microwave theory of ball lightning

    Science.gov (United States)

    Wu, H.-C.

    2016-06-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

  5. On the energy characteristics of ball lightning.

    Science.gov (United States)

    Bychkov, A V; Bychkov, V L; Abrahamson, John

    2002-01-15

    A compilation of 17 observations of ball lightning showing the most energetic effects is presented along with estimates of their energy content. These observations were chosen from several thousand for the much stronger interaction of each ball lightning on its surroundings, and the method of energy estimation outlined. The case is put that some of the observations show a higher energy than self-contained chemical energy could provide. Comments have been added to the paper, arguing that the energy estimations themselves should be consistent with whatever model is used for ball lightning. For example, the presence of reacting nanoparticles releasing chemical energy may bring about the same observed effects with lower estimated energy.

  6. Phase Stability of Intermetallic Compound Ce3Al in Mechanical Milling

    Science.gov (United States)

    Zhang, Yan-ping; Takeya, Hiroyuki; Sakurai, Kenji

    2017-11-01

    For many years, cerium-aluminum systems have been extensively studied because of their unusual magnetic behavior. As the atomic radii of cerium and aluminum differ greatly from each other, a solid solution is not obtained because of the Hume-Rothery rule. Therefore, intermetallic compounds are usually studied, and structural stability is crucial for further discussion of their physical properties. The present article reports on high-energy ball milling of the intermetallic compound Ce3Al at room temperature. It has been found that non-equilibrium supersaturated Ce solid solution was formed during the milling. The solubility of aluminum was estimated as 5 to 13 at. pct from the peak shifts of the X-ray diffraction pattern. The structural changes in the initial stages of the milling were also studied.

  7. Effect of ball to powder weight ratio on the mechanochemical synthesis of MoSi2-TiC nanocomposite powder

    Directory of Open Access Journals (Sweden)

    Mohamad Zakeri

    2012-12-01

    Full Text Available MoSi2-TiC nanocomposite powders were successfully synthesized with different ball to powder weight ratios (BPR by ball milling of Mo, Si, Ti and graphite elemental powders. Formation of this composite was studied by X-ray diffraction (XRD. Morphology and microstructure of the milled powders were monitored by scanning and transmission electron microscopy (SEM and TEM, respectively. There was incomplete formation in BPR 5:1 after 30 hours of milling, however, the formation of this composite was completed after 10 hours in BPRs 15:1 and 20:1. Higher BPRs with longer milling time led to partially transformation of β to α MoSi2. Based on Rietveld refinement analysis, and subsequent verification by TEM image, nanostructure powders with the mean grain size less than 25 nm were obtained in all BPRs. Very fine submicron powders in agglomerated ones for BPRs 10:1 and 15:1were obtained at the end of milling.

  8. Experimental investigations on effects of frequency in ultrasonically-assisted end-milling of AISI 316L: A feasibility study.

    Science.gov (United States)

    Maurotto, A; Wickramarachchi, C T

    2016-02-01

    The effects of frequency in ultrasonic vibration assisted milling (UVAM) with axial vibration of the cutter is investigated in this paper. A series of face-mill experiment in dry conditions were conducted on AISI 316L, an alloy of widespread use in industry. The finished surfaces roughness were studied along with basic considerations on tool wear for both conventional milling and an array of frequencies for UVAM (20–40–60 kHz) in a wide range of cutting conditions. Surface residual stresses and cross-cut metallographic slides were used to investigate the hidden effects of UVAM. Experimental results showed competitive results for both surface roughness and residual stress in UVAM when compared with conventional milling especially in the low range of frequency with similar trend for tool wear.

  9. Structural studies of Y2O3 dispersoids during mechanical milling and annealing in a Fe-15 Y2O3 model ODS alloy

    Science.gov (United States)

    Parida, Pradyumna Kumar; Dasgupta, Arup; Jayasankar, K.; Kamruddin, M.; Saroja, S.

    2013-10-01

    The Fe-15 wt% Y2O3 model Oxide Disperson Strengthened (ODS) alloy powder was prepared by mechanical milling in an inert atmosphere using high energy planetary ball mill. The present paper deals with the study on structural changes of nano-crystalline yttria dispersoids in Fe matrix during mechanical milling for various durations and subsequent annealing. The crystallinity of Y2O3 in the milled powder was studied by X-ray diffraction (XRD) technique which showed that the intensity of diffraction peaks of Y2O3 gradually disappeared with increase in milling time. Dark field TEM imaging of the milled powder showed that both Fe and Y2O3 particles were refined to few nanometers during milling. Electron diffraction analysis showed polycrystalline rings for Fe and broad rings with a few spots corresponding to the (4 1 1) plane of Y2O3 after 10 h of milling time. The yttria diffraction peaks became broad and diffuse with increasing milling time. Subsequent annealing of the 60 h milled powder at 1273 K for 1 h results in recrystallization of Y2O3 and growth of Fe crystallites.

  10. Japan steel mill perspective

    Energy Technology Data Exchange (ETDEWEB)

    Murase, K. [Kobe Steel Ltd., Tokyo (Japan)

    2004-07-01

    The international and Japan's steel industry, the coking coal market, and Japan's expectations from Canada's coal industry are discussed. Japan's steel mills are operating at full capacity. Crude steel production for the first half of 2004 was 55.8 million tons. The steel mills are profitable, but costs are high, and there are difficulties with procuring raw materials. Japan is trying to enhance the quality of coke, in order to achieve higher productivity in the production of pig iron. Economic growth is rising disproportionately in the BRICs (Brazil, Russia, India, and China), with a large increase in coking coal demand from China. On the supply side, there are several projects underway in Australia and Canada to increase production. These include new developments by Elk Valley Coal Corporation, Grande Cache Coal, Western Canadian Coal, and Northern Energy and Mining in Canada. The Elga Mine in the far eastern part of Russia is under development. But the market is expected to remain tight for some time. Japan envisions Canadian coal producers will provide a stable coal supply, expansion of production and infrastructure capabilities, and stabilization of price. 16 slides/overheads are included.

  11. Soccer ball lift coefficients via trajectory analysis

    Energy Technology Data Exchange (ETDEWEB)

    Goff, John Eric [Department of Physics, Lynchburg College, Lynchburg, VA 24501 (United States); Carre, Matt J, E-mail: goff@lynchburg.ed [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2010-07-15

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.

  12. Globalisierung im deutschen Profifußball

    OpenAIRE

    Hemmersbach, Tobias

    2003-01-01

    Zu den offenkundigen Veränderungen im deutschen Profifußball vor allem seit den 90er Jahren zählen die Internationalisierung des Spielermarktes und die Kommerzialisierung der Fußballindustrie. Überdies wurde mit der Einführung der Champions League in Anlehnung an die nationalen Ligen ein internationaler Vereinswettbewerb geschaffen, der in Teilen die Idee einer Europaliga verwirklicht. Diese Veränderungen lassen eine zunehmende Öffnung des deutschen gegenüber dem internationalen Profifußball ...

  13. Characteristics of Cu–Al2O3 composites of various starting particle size obtained by high-energy milling

    Directory of Open Access Journals (Sweden)

    VIŠESLAVA RAJKOVIĆ

    2009-05-01

    Full Text Available The powder Cu– Al2O3 composites were produced by high-energy milling. Various combinations of particle size and mixtures and approximately constant amount of Al2O3 were used as the starting materials. These powders were separately milled in air for up to 20 h in a planetary ball mill. The copper matrix was reinforced by internal oxidation and mechanical alloying. During the milling, internal oxidation of pre-alloyed Cu-2 mass %-Al powder generated 3.7 mass % Al2O3 nano-sized particles finely dispersed in the copper matrix. The effect of different size of the starting copper and Al2O3 powder particles on the lattice parameter, lattice distortion and grain size, as well as on the size, morphology and microstructure of the Cu– Al2O3 composite powder particles was studied.

  14. Enhanced antitumor activity of realgar mediated by milling it to nanosize

    Science.gov (United States)

    Tian, Ye; Wang, Xiaobo; Xi, Ronggang; Pan, Weisan; Jiang, Shuang; Li, Zhao; Zhao, Yu; Gao, Guanghui; Liu, Dan

    2014-01-01

    Realgar is a poorly water-soluble compound that exhibits poor bioavailability. To improve this, the authors reduced the particle size of realgar to nanoscale by high-energy ball milling and optimized the preparation process under which (realgar weight 40 g, milling time 9 hours, milling speed 38 Hz, milling temperature −20°C) realgar nanoparticles (NPs) with an average size of 78±8.3 nm were prepared. The average particle size of realgar was characterized by laser scattering, and its apparent shape was observed by transmission electron microscopy and scanning electron microscopy. The solubility of realgar was enhanced after milling until the particles were in the nanoscale region without altering its properties, as confirmed by a scanning electron microscopy energy-dispersive spectrometer. Realgar NPs had higher cytotoxicity on the selected cell lines, namely human breast cancer (MCF7), human hepatoma (HepG2), and human lung cancer (A549) cell lines, than coarse realgar. In addition, a pharmacokinetics study performed in rats indicated that the relative bioavailability of realgar NPs was 216.9% compared with coarse realgar; a biodistribution study performed in mice showed that after intragastric administration of realgar NPs, higher arsenic concentration was reached in the tumor, heart, liver, spleen, lung, and kidney compared with the administration of coarse realgar, as confirmed by inductively coupled plasma mass spectrometry to determine the concentration of arsenic. This study indicated that high-energy ball milling is an effective way to reduce the average particle size of realgar, and compared with coarse realgar, the cytotoxicity and bioavailability of realgar NPs were significantly improved. PMID:24516332

  15. Enhanced antitumor activity of realgar mediated by milling it to nanosize.

    Science.gov (United States)

    Tian, Ye; Wang, Xiaobo; Xi, Ronggang; Pan, Weisan; Jiang, Shuang; Li, Zhao; Zhao, Yu; Gao, Guanghui; Liu, Dan

    2014-01-01

    Realgar is a poorly water-soluble compound that exhibits poor bioavailability. To improve this, the authors reduced the particle size of realgar to nanoscale by high-energy ball milling and optimized the preparation process under which (realgar weight 40 g, milling time 9 hours, milling speed 38 Hz, milling temperature -20°C) realgar nanoparticles (NPs) with an average size of 78 ± 8.3 nm were prepared. The average particle size of realgar was characterized by laser scattering, and its apparent shape was observed by transmission electron microscopy and scanning electron microscopy. The solubility of realgar was enhanced after milling until the particles were in the nanoscale region without altering its properties, as confirmed by a scanning electron microscopy energy-dispersive spectrometer. Realgar NPs had higher cytotoxicity on the selected cell lines, namely human breast cancer (MCF7), human hepatoma (HepG2), and human lung cancer (A549) cell lines, than coarse realgar. In addition, a pharmacokinetics study performed in rats indicated that the relative bioavailability of realgar NPs was 216.9% compared with coarse realgar; a biodistribution study performed in mice showed that after intragastric administration of realgar NPs, higher arsenic concentration was reached in the tumor, heart, liver, spleen, lung, and kidney compared with the administration of coarse realgar, as confirmed by inductively coupled plasma mass spectrometry to determine the concentration of arsenic. This study indicated that high-energy ball milling is an effective way to reduce the average particle size of realgar, and compared with coarse realgar, the cytotoxicity and bioavailability of realgar NPs were significantly improved.

  16. Finite Element Simulation of the Vibration Provided by Sandwich Rigid Panel with a Resilient Material In Between under Heavyweight Impact

    Directory of Open Access Journals (Sweden)

    Shun-Fa Hwang

    2014-01-01

    Full Text Available The purpose of the present work is to use an explicit finite element code to model the impact behavior of a heavyweight impact source like rubber ball and to predict the floor impact vibration of resilient materials, which are used in the floor coverings construction for sound insulation. To simulate the impact force of rubber balls, the hyperviscoelastic rubber model is applied. Then, this rubber model is used in the simulation for the impact vibration of resilient materials. The results indicate that the hyperviscoelastic rubber model could precisely simulate the impact force of rubber balls, as its two parameters are properly chosen according to the desired impact force. Also, the present model could capture the impact and vibration behavior of the considered materials and reasonably evaluate the insulation effect of resilient materials.

  17. From a Ball Game to Incompleteness

    Indian Academy of Sciences (India)

    We present a ball game that can be continued as long as we wish. It looks as though the game would never end. But by applying a result on trees, we show that the game nonetheless ends in some finite number of moves. We then point out some deep results on the natural number system connected with the game.

  18. Tennis Ball Flight under Strong Wind

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 11. Tennis Ball Flight under Strong Wind. K R Y Simha. Classroom Volume 7 Issue 11 November 2002 pp 70-76. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/007/11/0070-0076. Author Affiliations.

  19. A plasma ball in the Microcosm museum

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Plasma balls, like the one shown here, are displayed in the Microcosm exhibition where families can visit to learn more about the experiments carried out in a research institute like CERN. Hands-on activities allow visitors to get a step closer to the research activities carried out at CERN.

  20. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  1. The dynamic behavior of squash balls

    Science.gov (United States)

    Lewis, Gareth J.; Arnold, J. Cris; Griffiths, Iwan W.

    2011-03-01

    The behavior of a squash ball constitutes an excellent case study of the dynamic behavior of rubbery materials. It is shown that the complex viscoelastic behavior of rubber can be investigated using simple drop bounce tests and compression tests. The drop tests show that the coefficient of restitution increases as the ball temperature increases. The compression tests show that as the speed of compression increases or as the ball temperature decreases, the compressive force and the energy loss both increase. These effects are due to the viscoelastic nature of the rubber and are an excellent example of the time-temperature equivalence of polymers. Compression tests were performed on balls with small holes at the base to separate the effects of the internal air pressure from the material deformation. It was found that the internal air pressure contributed about one-third to the compressive force, but contributed little to energy loss. This behavior shows that the rubber material dominates the rebound behavior and that the normal warming up process at the start of a squash game is important to raise the temperature of the rubber rather than to increase the internal air pressure.

  2. Holomorphic Spaces in the Unit Ball of

    Directory of Open Access Journals (Sweden)

    Augusto Guadalupe Miss Paredes

    2013-01-01

    Full Text Available We introduce the and vector spaces of holomorphic functions defined in the unit ball of , generalizing previous work like Ouyang et al. (1998, Stroethoff (1989, and Choa et al. (1992. Likewise, we characterize those spaces in terms of harmonic majorants as a generalization of Arellano et al. (2000.

  3. Soccer Ball Production for Nike in Pakistan

    NARCIS (Netherlands)

    K.A. Siegmann (Karin Astrid)

    2008-01-01

    textabstractThis paper looks at how Nike’s soccer ball suppliers (previous and current) in Sialkot (Pakistan) fare in relation to the company’s code of ethics. While minimum required working conditions are implemented, the criteria for social and environmental compliance are not met with. The

  4. Effect of Heat Treatment on the Microstructure and Tensile Deformation Behavior of Oxide Dispersion Strengthened Alloys Manufactured by Complex Milling Process

    Directory of Open Access Journals (Sweden)

    Kim Y.-K.

    2017-06-01

    Full Text Available This study attempted to manufacture an ODS alloy by combining multiple milling processes in mechanical alloying stage to achieve high strength and fracture elongation. The complex milling process of this study conducted planetary ball milling, cryogenic ball milling and drum ball milling in sequential order, and then the microstructure and tensile deformation behavior were investigated after additional heat treatment. The oxide particles distributed within the microstructure were fine oxide particles of 5~20 nm and coarse oxide particles of 100~200 nm, and the oxide particles were confirmed to be composed of Cr, Ti, Y and O. Results of tensile tests at room temperature measured yield strength, tensile strength and elongation as 1320 MPa, 2245 MPa and 4.2%, respectively, before heat treatment, and 1161 MPa, 2020 MPa and 5.5% after heat treatment. This results indicate that the ODS alloy of this study gained very high strengths compared to other known ODS alloys, allowing greater plastic zones.

  5. Machining Chatter Analysis for High Speed Milling Operations

    Science.gov (United States)

    Sekar, M.; Kantharaj, I.; Amit Siddhappa, Savale

    2017-10-01

    Chatter in high speed milling is characterized by time delay differential equations (DDE). Since closed form solution exists only for simple cases, the governing non-linear DDEs of chatter problems are solved by various numerical methods. Custom codes to solve DDEs are tedious to build, implement and not error free and robust. On the other hand, software packages provide solution to DDEs, however they are not straight forward to implement. In this paper an easy way to solve DDE of chatter in milling is proposed and implemented with MATLAB. Time domain solution permits the study and model of non-linear effects of chatter vibration with ease. Time domain results are presented for various stable and unstable conditions of cut and compared with stability lobe diagrams.

  6. Detecting supersymmetric Q-balls with neutron stars

    OpenAIRE

    Madsen, Jes

    1998-01-01

    Supersymmetric Q-balls trapped in neutron stars or white dwarfs may cause the stars to explode. Trapping of Q-balls in neutron stars is shown to be less likely, but trapping in neutron star progenitors more likely than hitherto assumed, making neutron stars very sensitive Q-ball "detectors". White dwarfs only trap potentially dangerous Q-balls in a narrow parameter range.

  7. Magnetic properties of ball-milled TbFe2 and TbFe2B

    Indian Academy of Sciences (India)

    Unknown

    Dhilsha and Rama Rao (1990) reported single particle excitations in Co substituted Ho0⋅85Tb0⋅15Fe2, through ele- ctrical resistivity measurements. Low temperature mag- netization studies on Ni substituted Dy0⋅73Tb0.27Fe2 and. Ho0⋅85Tb0⋅15Fe2 have revealed domain wall pinning (Senthil. Kumar et al 1995).

  8. HPMC as a potential enhancer of nimodipine biopharmaceutical properties via ball-milled solid dispersions.

    Science.gov (United States)

    Riekes, Manoela Klüppel; Kuminek, Gislaine; Rauber, Gabriela Schneider; de Campos, Carlos Eduardo Maduro; Bortoluzzi, Adailton João; Stulzer, Hellen Karine

    2014-01-01

    The poor solubility of drugs remains one of the most challenging aspects of formulation development. Aiming at improving the biopharmaceutical limitations of the calcium channel blocker nimodipine, the development of solid dispersions is proposed herein. Three different proportions of nimodipine:HPMC were tested and all of them generated amorphous solid dispersions. Improvements of up 318% in the solubility and a 4-fold increase in the dissolution rate of nimodipine were achieved. Stability studies conducted over 90 days in a desiccator indicated that the initial characteristic of the formulations were maintained. However, at 40 °C/75% RH recrystallization was observed for solid dispersions with 70 and 80% of HPMC, whilst the formulation composed of 90% of the carrier remained amorphous. The increase in the stability observed when the HPMC concentration was increased from 70 to 90% in the solid dispersions was attributed to the dilution mechanism. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Improvement of hydrogen storage kinetics in ball-milled magnesium doped with antimony

    Czech Academy of Sciences Publication Activity Database

    Čermák, Jiří; Král, Lubomír; Roupcová, Pavla

    2017-01-01

    Roč. 42, č. 9 (2017), s. 6144-6151 ISSN 0360-3199 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : Hydrogen * Hydrogen storage * Storage capacity * Magnesium alloys * Antimony Subject RIV: JJ - Other Materials Impact factor: 3.582, year: 2016

  10. Energy density calculations for ball-lightning-like luminous silicon balls

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Gerson S; Ferreira, Joacy V; Bastos, Cristiano C; Dos Santos, Marcus V; Pavao, Antonio C [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Pernambuco (Brazil)

    2010-05-11

    The energy density of a luminous silicon ball [Phys. Rev. Lett. 98 048501 (2007)] is calculated for a model with a metal core surrounded by an atmosphere of silicon oxides. Experimental data combined with the molecular orbital calculations of the oxidation enthalpy lead to a mean energy density of 3.9 MJ m{sup -3}, which is within the range of estimates from other ball lightning models. This result provides good evidence to support the silicon-based model. (methodological notes)

  11. METHODOLOGICAL NOTES: Energy density calculations for ball-lightning-like luminous silicon balls

    Science.gov (United States)

    Paiva, Gerson S.; Ferreira, Joacy V.; Bastos, Cristiano C.; dos Santos, Marcus V.; Pavão, Antonio C.

    2010-05-01

    The energy density of a luminous silicon ball [Phys. Rev. Lett. 98 048501 (2007)] is calculated for a model with a metal core surrounded by an atmosphere of silicon oxides. Experimental data combined with the molecular orbital calculations of the oxidation enthalpy lead to a mean energy density of 3.9 MJ m-3, which is within the range of estimates from other ball lightning models. This result provides good evidence to support the silicon-based model.

  12. Colored Ball Position Tracking Method For Goalkeeper Humanoid Robot Soccer

    Directory of Open Access Journals (Sweden)

    Nuryono Satya Widodo

    2013-03-01

    Full Text Available In a robot soccer game, robots must have ability to find position of the ball. The ball usually has particularly specified color and contrast with the color of the field. Goalkeeper robot must be able to detect the exact position of the ball so that it can block the ball into the goal. Identifying the location of the colored balls using robot vision becomes very important in addition to the mechanical motion of the robot. This paper proposed method to track colored ball position. First, image video captured with web camera, then for each frame in the video, the color filtering based on HSL color model performed. After that, images from filtering process are to be detected its blob, by labeling connected components nearby. The largest blob in image represents detected object. The next step is detection of ball position using 9-Cells coordinate. Ball position coordinate is updated in some period of time through the mechanism of object position updater and then sends to robot controller to control the robot's movements appropriately. Method is implemented into a computer application of colored ball tracking system on the robot. System is able to detect the presence of the ball by a specific color in the HSL color model. Ball position coordinates can be detected by the system in 9-Cellss coordinate for goalkeeper robot soccer to block the ball.

  13. Interrelation between ball lightning and optically induced forces

    Science.gov (United States)

    Torchigin, V. P.; Torchigin, A. V.

    2013-09-01

    Optically induced forces are considered as a key factor for explaining the phenomenon of ball lightning. They can provide not only the existence of ball lightning in the form of self-confined intense white light circulating in a spherical shell of air strongly compressed by the light but also the anomalous motion of ball lightning in the terrestrial atmosphere.

  14. Temperature and Coefficient of Restitution of a Table Tennis Ball

    Directory of Open Access Journals (Sweden)

    Yoonyoung Chang

    2016-01-01

    Full Text Available The coefficient of restitution (COR of a bouncing table tennis ball was measured at varying ball temperatures with a Motion Detector. It was found that there is a negative linear relationship between the COR and the temperature of the table tennis ball for temperatures ranging from 5 to 56 ̊C.

  15. Measuring the Rebound Resilience of a Bouncing Ball

    Science.gov (United States)

    Wadhwa, Ajay

    2012-01-01

    Some balls which are made of high-quality rubber (an elastomeric) material, such as tennis or squash balls, could be used for the determination of an important property of such materials called resilience. Since a bouncing ball involves a single impact we call this property "rebound resilience" and express it as the ratio of the rebound height to…

  16. The economics of sugar mill waste management in the Australian Sugar Industry: Mill mud case study

    OpenAIRE

    Qureshi, Muhammad Ejaz; Wegener, Malcolm K.; Mallawaarachchi, Thilak

    2001-01-01

    Sugar mills produce a range of by-products during the process of sugar extraction. Mill mud is one of the by-products that is produced in significant volume. Often mill mud is mixed with mill ash from the firing of bagasse, which together forms the bulk of mill waste available for disposal from raw sugar mills. The practice of spreading mill mud over nearby cane fields has been the primary means of disposing mill mud for many years. Mills generally promote the practice by offering freight sub...

  17. Influence of Milling Media on the Mechanical Alloyed W-0.5 wt.% Ti Powder Alloy

    Directory of Open Access Journals (Sweden)

    Hadi Jahangiri

    2016-01-01

    Full Text Available The effects of milling atmosphere and mechanical alloying (MA duration on the effective lattice parameter, crystallite size, lattice strain, and amorphization rate of the W-0.5 wt.% Ti powders were investigated. W-0.5 wt.% Ti powders were mechanically alloyed (MA’d for 10 h and 20 h in a high energy ball mill. Moreover, morphology of the powders for various MA was analyzed using SEM microscopy. Their powder density was also measured by helium pycnometer. The dry milled agglomerated powders have spherical particle, while wet milled powders have layered morphology. Milling media and increasing of milling time significantly reduce the crystallite size. The smallest crystallite size is 4.93 nm which belonged to the dry milled powders measured by Lorentzian method after 20 hours’ MA. However, after 20 hours, MA’d powders show the biggest crystallite size, as big as 57.07 nm, measured with the same method in ethanol.

  18. Measuring unbalance-induced vibrations in rotating tools

    Directory of Open Access Journals (Sweden)

    Kimmelmann Martin

    2017-01-01

    Full Text Available Unbalances in a tool cause vibrations of the spindle and the machine itself and lead to a waviness of the machined workpiece surface. This paper presents an experimental and analytical procedure for optically measuring the unbalance-induced displacements of the tool centre point (TCP. Therefore, a new method is introduced to determine the dynamic vibrations of a tool by comparing the geometrical profile of the tool with the dynamical profile at a high rotational speed. The necessary steps for measuring the signals and calculating the underlying dynamic vibrations of the tool are presented here. Afterwards, the unbalance-induced vibrations of a milling tool are shown as well as their influence on the eccentricity of the rotation axis. With this newly introduced method it is possible to directly link the displacements of the tool under rotation to the waviness of the workpiece surface and the dynamic stiffness of machine tools.

  19. Actuator design for vibration assisted machining of high performance materials with ultrasonically modulated cutting speed

    Science.gov (United States)

    Rinck, Philipp M.; Sitzberger, Sebastian; Zaeh, Michael F.

    2017-06-01

    In vibration assisted machining, an additional high-frequency oscillation is superimposed on the kinematics of the conventional machining process. This generates oscillations on the cutting edge in the range of a few micrometers, thereby causing a high-frequency change in the cutting speed or the feed. Consequently, a reduction of cutting forces, an increase of the tool life as well as an improvement of the workpiece quality can be achieved. In milling and grinding it has been shown that these effects are already partially present in the case of a vibration excitation in axial direction relative to the workpiece, which is perpendicular to the cutting direction. Further improvements of the process results can be achieved by superimposing a vibration in cutting direction and thus modifying the cutting speed at high frequency. The presented work shows the design of an ultrasonic actuator that enables vibration-assisted milling and grinding with ultrasonically modulated cutting speed. The actuator system superimposes a longitudinal torsional ultrasonic oscillation to the milling or grinding tool. It uses a bolt clamped Langevin transducer and a helically slotted horn, which degenerates the longitudinal vibration into a combined longitudinal torsional (L-T) vibration at the output surface. A finite element analysis is used to determine the vibration resonance frequency and mode shapes to maximize the torsional output. Afterwards, the simulation has been experimentally validated.

  20. corn-mill grinding plates

    African Journals Online (AJOL)

    manufactured corn-mill grinding plates to investigate the possible causes of their early wear and failure. Three different samples selected from the same local manufacturer were tested for chemical composition and micro- structural, as well as wear ...

  1. Aerodynamic effects of dimples on soccer ball surfaces.

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi

    2017-10-01

    Recently, the shape and design of the panel on the official ball used in the FIFA World Cup was considerably different from that of a conventional soccer ball (having 32 pentagonal and hexagonal panels). Depending on the number of different panels and their orientation, the aerodynamic force experienced by a ball is believed to change, which in turn changes the ball trajectory. However, not much is known about the impact of the surface forms of a ball on its aerodynamics. Therefore, in the present study, 10 different types of soccer balls were produced and their aerodynamic properties were studied by wind tunnel experiments. The results confirmed that the aerodynamic force acting on the ball varied considerably depending on the existence of dimples on the ball surface. In addition, the 4 types of soccer balls, which had different kinds of roughness, revealed that even balls having the same number and shapes of panels experienced greatly varying aerodynamic forces depending on the surface form of the balls.

  2. Aerodynamic effects of dimples on soccer ball surfaces

    Directory of Open Access Journals (Sweden)

    Sungchan Hong

    2017-10-01

    Full Text Available Recently, the shape and design of the panel on the official ball used in the FIFA World Cup was considerably different from that of a conventional soccer ball (having 32 pentagonal and hexagonal panels. Depending on the number of different panels and their orientation, the aerodynamic force experienced by a ball is believed to change, which in turn changes the ball trajectory. However, not much is known about the impact of the surface forms of a ball on its aerodynamics. Therefore, in the present study, 10 different types of soccer balls were produced and their aerodynamic properties were studied by wind tunnel experiments. The results confirmed that the aerodynamic force acting on the ball varied considerably depending on the existence of dimples on the ball surface. In addition, the 4 types of soccer balls, which had different kinds of roughness, revealed that even balls having the same number and shapes of panels experienced greatly varying aerodynamic forces depending on the surface form of the balls. Keywords: Engineering, Mechanics

  3. The strange flight behaviour of slowly spinning soccer balls

    Science.gov (United States)

    Mizota, Taketo; Kurogi, Kouhei; Ohya, Yuji; Okajima, Atsushi; Naruo, Takeshi; Kawamura, Yoshiyuki

    2013-05-01

    The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights.

  4. Classical Yang-Mills potentials

    Energy Technology Data Exchange (ETDEWEB)

    Mandula, J.E.

    1976-12-15

    Classical Coulomb-type configurations of Yang-Mills fields coupled to external sources (charges) are described and discussed. They are shown to be stable against small classical fluctuations in the fields if the Yang-Mills coupling is sufficiently small. In developing the stability analysis, massless charged scalar fields in the presence of a weak Coulomb potential are also shown to be stable to small field fluctuations. (AIP)

  5. Chalk Line Mill, Anniston, AL

    Science.gov (United States)

    The Chalk Line Mill property was the site of a textile mill which operated from 1887 until 1994. Demolition activities in 2004 removed most of the structures on-site, but also left large, unsightly piles of debris scattered across this 14-acre property. The City applied for and received a $200,000 Brownfields cleanup grant in 2007 to address contamination on the property and the Appalachian Regional Commission provided an additional $150,000 in funding.

  6. Ball Machine Usage in Tennis: Movement Initiation and Swing Timing While Returning Balls from a Ball Machine and from a Real Server

    Directory of Open Access Journals (Sweden)

    Jan Carboch, Vladimir Süss, Tomas Kocib

    2014-06-01

    Full Text Available Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server. Receivers’ movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing.

  7. Effects of ultrasonic vibration on microstructure and mechanical properties of nano-sized SiC particles reinforced Al-5Cu composites.

    Science.gov (United States)

    Li, Jianyu; Lü, Shulin; Wu, Shusen; Gao, Qi

    2018-04-01

    Ultrasonic vibration (UV) treatment has been successfully applied to improve the particles distribution of nano-sized SiC particles (SiC p ) reinforced Al-5Cu alloy matrix composites which were prepared by combined processes of dry high energy ball milling and squeeze casting. When UV treatment is applied, the distribution of nano-sized SiC p has been greatly improved. After UV for 1 min, large particles aggregates are broken up into small aggregates due to effects of cavitation and the acoustic streaming. After UV for 5 min, all the particles aggregates are dispersed and the particles are uniformly distributed in the composites. Compared with the Al-5Cu matrix alloy, the ultimate tensile strength, yield strength and elongation of the 1 wt% nano-sized SiC p /Al-5Cu composites treated by UV for 5 min are 270 MPa, 173 MPa and 13.3%, which are increased by 7.6%, 6.8% and 29%, respectively. The improvements of mechanical properties after UV are attributed to the uniform distribution of nano particles, grain refinement of aluminum matrix alloy and reduction of porosity in the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Evolution of the quadrupole hyperfine interaction while milling a Si-HfO{sub 2} blend

    Energy Technology Data Exchange (ETDEWEB)

    Chain, C.Y., E-mail: yamil@fisica.unlp.edu.ar [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Ferrari, S.; Damonte, L.C. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Martinez, J.A.; Pasquevich, A.F. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC-PBA) (Argentina)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Perturbed angular correlations and X-ray diffraction studies in equimolar Si-HfO{sub 2}. Black-Right-Pointing-Pointer Mixture subjected to progressive mechanical milling and a final annealing. Black-Right-Pointing-Pointer Short milling distorts monoclinic hafnia to tetragonal forms. Black-Right-Pointing-Pointer Long milling forms hafnon precursor. Black-Right-Pointing-Pointer Moderate temperature annealing ends in hafnon. - Abstract: As HfO{sub 2} appears as a good candidate to replace SiO{sub 2} in Si complementary metal-oxide-semiconductor devices, a refined knowledge of the possible solid-state reactions between Si and HfO{sub 2} is valuable. Being the Perturbed Angular Correlations technique a very sensitive method to detect small changes in solid state, the goal of this work is to follow the different stages that occur while ball milling a blend Si-HfO{sub 2} by inspecting the hyperfine quadrupole interaction at Hf sites. The characterization is complemented by X-ray diffraction analysis. For comparison, a similar study on pure m-HfO{sub 2} is carried out. The results seem to reveal a gradual incorporation of Si in a tetragonal defective phase of hafnia with milling time. In addition, the formation of precursor arrays of the HfSiO{sub 4} structure takes place. After an annealing at 1000 Degree-Sign C an important amount of crystalline hafnon appears.

  9. Collisional and collisionless expansion of Yukawa balls.

    Science.gov (United States)

    Piel, Alexander; Goree, John A

    2013-12-01

    The expansion of Yukawa balls is studied by means of molecular dynamics simulations of collisionless and collisional situations. High computation speed was achieved by using the parallel computing power of graphics processing units. When the radius of the Yukawa ball is large compared to the shielding length, the expansion process starts with the blow-off of the outermost layer. A rarefactive wave subsequently propagates radially inward at the speed of longitudinal phonons. This mechanism is fundamentally different from Coulomb explosions, which employ a self-similar expansion of the entire system. In the collisionless limit, the outer layers carry away most of the available energy. The simulations are compared with analytical estimates. In the collisional case, the expansion process can be described by a nonlinear diffusion equation that is a special case of the porous medium equation.

  10. Dust ball physics and the Schwarzschild metric

    CERN Document Server

    Kassner, Klaus

    2016-01-01

    A physics-first derivation of the Schwarzschild metric is given. Gravitation is described in terms of the effects of tidal forces (or of spacetime curvature) on the volume of a small ball of test particles (a dust ball), freely falling after all particles were at rest with respect to each other initially. The possibility to express Einstein's equation this way and some of its ramifications have been enjoyably discussed by Baez and Bunn [Am. J. Phys. 73, 644 (2005)]. Since the formulation avoids the use of tensors, neither advanced tensor calculus nor sophisticated differential geometry are needed in the calculation. The derivation is not lengthy and it has visual appeal, so it may be useful in teaching.

  11. Free-floating atmospheric pressure ball plasmas

    Science.gov (United States)

    Wurden, G. A.; Ticos, C.; Wang, Z.; Wurden, C. J. V.

    2007-11-01

    A long-lived (0.3 second, 10-20 cm diameter) ball plasma floating in the air above a water surface has been formed and studied in the laboratory. A 0.4 - 1 mF capacitor is charged to 4-5 kV, and subsequently discharged (30-60 Amps, 20-50 msec duration) into central copper cathode held fixed just below the surface of a bucket of water (with a weak solution of various salts in distilled water, such as CuSO4 or CuCl2, LiCl or NaCl). An underwater ring anode completes the circuit. A bubble of hot vapor from the water surface rises up in the first few milliseconds, and changes from a mushroom cloud with stalk, to a detached quasi-spherical object, finally evolving into a vortex ring. The plasma consists of ionized water vapor, with positive salts and OH- radicals, as well as molecular species, and it completely excludes nitrogen or oxygen from the rising plasma structure. A fine boundary layer is visible in orange, in contrast to a green ball interior when using Cu/CuSO4, and filamentary structures are visible at late times. Finally, a whisp of smoke ring is observed as a residue. A variety of visible and infrared imaging (both video and still cameras) are used, along with 200-800 nm time & space resolved spectroscopy, to identify features of this laboratory analog to ball lightning. Possible applications include a windowless ball- plasma powered pulsed copper vapor laser operating at 510 nm.

  12. Relativistic-microwave theory of ball lightning

    OpenAIRE

    H.-C. Wu

    2016-01-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by partic...

  13. High-temperature Mossbauer spectroscopy of mechanically milled NiFe2O4

    DEFF Research Database (Denmark)

    Helgason, O.; Jiang, Jianzhong

    2002-01-01

    Oxide spinels, in particular those containing iron, often exhibit technically important electrical- and magnetic-properties. We report here on X-ray powder diffraction and Mossbauer studies of nanostructured NiFe2O4 particles prepared by high-energy ball milling from bulk NiFe2O4, which is an inv......Oxide spinels, in particular those containing iron, often exhibit technically important electrical- and magnetic-properties. We report here on X-ray powder diffraction and Mossbauer studies of nanostructured NiFe2O4 particles prepared by high-energy ball milling from bulk NiFe2O4, which...... is an inverse spinel. The Mossbauer spectra were recorded in situ at different temperatures in the range of 300-850 K. The Mossbauer spectra of the milled samples show a broad distribution of magnetic hyperfine fields together with a paramagnetic state at room temperature. Initially, at 700 K the spectrum...... is mainly paramagnetic, but during the process of annealing, magnetic sextets emerge. The treatment results in a significant change in the B/A area ratio of the ferrite. The Neel temperature of the samples is estimated from the B(T) relation to be in the range of 800-850 K....

  14. 3D Printing of Ball Grid Arrays

    Science.gov (United States)

    Sinha, Shayandev; Hines, Daniel; Dasgupta, Abhijit; Das, Siddhartha

    Ball grid arrays (BGA) are interconnects between an integrated circuit (IC) and a printed circuit board (PCB), that are used for surface mounting electronic components. Typically, lead free alloys are used to make solder balls which, after a reflow process, establish a mechanical and electrical connection between the IC and the PCB. High temperature processing is required for most of these alloys leading to thermal shock causing damage to ICs. For producing flexible circuits on a polymer substrate, there is a requirement for low temperature processing capabilities (around 150 C) and for reducing strain from mechanical stresses. Additive manufacturing techniques can provide an alternative methodology for fabricating BGAs as a direct replacement for standard solder bumped BGAs. We have developed aerosol jet (AJ) printing methods to fabricate a polymer bumped BGA. As a demonstration of the process developed, a daisy chain test chip was polymer bumped using an AJ printed ultra violet (UV) curable polymer ink that was then coated with an AJ printed silver nanoparticle laden ink as a conducting layer printed over the polymer bump. The structure for the balls were achieved by printing the polymer ink using a specific toolpath coupled with in-situ UV curing of the polymer which provided good control over the shape, resulting in well-formed spherical bumps on the order of 200 um wide by 200 um tall for this initial demonstration. A detailed discussion of the AJ printing method and results from accelerated life-time testing will be presented

  15. Tunable Passive Vibration Suppressor

    Science.gov (United States)

    Boechler, Nicholas (Inventor); Dillon, Robert Peter (Inventor); Daraio, Chiara (Inventor); Davis, Gregory L. (Inventor); Shapiro, Andrew A. (Inventor); Borgonia, John Paul C. (Inventor); Kahn, Daniel Louis (Inventor)

    2016-01-01

    An apparatus and method for vibration suppression using a granular particle chain. The granular particle chain is statically compressed and the end particles of the chain are attached to a payload and vibration source. The properties of the granular particles along with the amount of static compression are chosen to provide desired filtering of vibrations.

  16. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.

  17. Relation Between Hertz Stress-Life Exponent, Ball-Race Conformity, and Ball Bearing Life

    Science.gov (United States)

    Zaretsky, Erwin V.; Poplawski, Joseph V.; Root, Lawrence E.

    2008-01-01

    ANSI/ABMA and ISO standards based on Lundberg-Palmgren bearing life theory are normalized for ball bearings having inner- and outerrace conformities of 52 percent (0.52) and made from pre-1940 bearing steel. The Lundberg-Palmgren theory incorporates an inverse 9th power relation between Hertz stress and fatigue life for ball bearings. The effect of race conformity on ball set life independent of race life is not incorporated into the Lundberg-Palmgren theory. In addition, post-1960 vacuum-processed bearing steel exhibits a 12th power relation between Hertz stress and life. The work reported extends the previous work of Zaretsky, Poplawski, and Root to calculate changes in bearing life--that includes the life of the ball set--caused by race conformity, Hertz stress-life exponent, ball bearing type and bearing series. The bearing fatigue life in actual application will usually be equal to or greater than that calculated using the ANSI/ABMA and ISO standards that incorporate the Lundberg-Palmgren theory. The relative fatigue life of an individual race is more sensitive to changes in race conformity for Hertz stress-life exponent n of 12 than where n = 9. However, when the effects are combined to predict actual bearing life for a specified set of conditions and bearing geometry, the predicted life of the bearing will be greater for a value of n = 12 than n = 9.

  18. SUBAQUEOUS DISPOSAL OF MILL TAILINGS

    Energy Technology Data Exchange (ETDEWEB)

    Neeraj K. Mendiratta; Roe-Hoan Yoon; Paul Richardson

    1999-09-03

    A study of mill tailings and sulfide minerals was carried out in order to understand their behavior under subaqueous conditions. A series of electrochemical experiments, namely, cyclic voltammetry, electrochemical impedance spectroscopy and galvanic coupling tests were carried out in artificial seawater and in pH 6.8 buffer solutions with chloride and ferric salts. Two mill tailings samples, one from the Kensington Mine, Alaska, and the other from the Holden Mine, Washington, were studied along with pyrite, galena, chalcopyrite and copper-activated sphalerite. SEM analysis of mill tailings revealed absence of sulfide minerals from the Kensington Mine mill tailings, whereas the Holden Mine mill tailings contained approximately 8% pyrite and 1% sphalerite. In order to conduct electrochemical tests, carbon matrix composite (CMC) electrodes of mill tailings, pyrite and galena were prepared and their feasibility was established by conducting a series of cyclic voltammetry tests. The cyclic voltammetry experiments carried out in artificial seawater and pH 6.8 buffer with chloride salts showed that chloride ions play an important role in the redox processes of sulfide minerals. For pyrite and galena, peaks were observed for the formation of chloride complexes, whereas pitting behavior was observed for the CMC electrodes of the Kensington Mine mill tailings. The electrochemical impedance spectroscopy conducted in artificial seawater provided with the Nyquist plots of pyrite and galena. The Nyquist plots of pyrite and galena exhibited an inert range of potential indicating a slower rate of leaching of sulfide minerals in marine environments. The galvanic coupling experiments were carried out to study the oxidation of sulfide minerals in the absence of oxygen. It was shown that in the absence of oxygen, ferric (Fe3+) ions might oxidize the sulfide minerals, thereby releasing undesirable oxidation products in the marine environment. The source of Fe{sup 3{minus}} ions may be

  19. Effect of milling parameters on sinterability, mechanical and electrical properties of Cu-4 wt.% ZrO{sub 2} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Taha, Mohammed A., E-mail: mtahanrc@gmail.com [Solid-State Physics Department, National Research Centre, El-Buhooth St., 12622, Dokki, Cairo (Egypt); Nassar, Amira H. [Solid-State Physics Department, National Research Centre, El-Buhooth St., 12622, Dokki, Cairo (Egypt); Zawrah, M.F. [Ceramics Department, National Research Centre, El-Buhooth St., 12622, Dokki, Cairo (Egypt)

    2016-09-15

    Mechanical alloying was used to produce Cu matrix nanocomposite reinforced by 4 wt.% ZrO{sub 2} nanoparticles with different milling time up to 16 h and ball-to-powder ratios (BPRs) up to 40:1. The milled nanocomposite powders were investigated by X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). To study the sinterability, the milled powders were cold pressed and sintered at 800 °C for 1 h in argon atmosphere. In order to investigate the relative density and microstructures of the sintered nanocomposites, scanning electron microscopy (SEM) as well as energy dispersive spectrometer (EDS) were employed. The electrical and mechanical properties of the sintered nanocomposites were also examined. The results revealed that a uniform distribution of ZrO{sub 2} reinforcement in Cu matrix was successfully obtained and the agglomeration, crystal and particle sizes were decreased after either milling times and/or BPRs. The results also pointed out that the relative density, microhardness, compressive strength and electrical conductivity of the sintered nanocomposite samples were increased with the increasing of milling time and/or BPRs while apparent porosity was decreased. The maximum values of microhardness, compressive strength and electrical conductivity were 872 MPa, 304 MPa and 45.9% IACS, respectively for the milled sample for 16 h and BRP 40:1. - Highlights: • Cu-4 wt.% ZrO{sub 2} nanoparticles with different parameter by mechanical alloying. • The increased milling times and/or BPRs led to a decrease in the particle size. • Microhardness is increased with increasing ball-to-powder weight ratios. • Compressive strength is increased with increasing milling time. • Electrical conductivity of the samples was increasing with increase milling time.

  20. Aerodynamics in the classroom and at the ball park

    Science.gov (United States)

    Cross, Rod

    2012-04-01

    Experiments suitable for classroom projects or demonstrations are described concerning the aerodynamics of polystyrene balls. A light ball with sufficient backspin can curve vertically upward through the air, defying gravity and providing a dramatic visual demonstration of the Magnus effect. A ball projected with backspin can also curve downward with a vertical acceleration greater than that due to gravity if the Magnus force is negative. These effects were investigated by filming the flight of balls projected in an approximately horizontal direction so that the lift and drag forces could be easily measured. The balls were also fitted with artificial raised seams and projected with backspin toward a vertical target in order to measure the sideways deflection over a known horizontal distance. It was found that (a) a ball with a seam on one side can deflect either left or right depending on its launch speed and (b) a ball with a baseball seam can also deflect sideways even when there is no sideways component of the drag or lift forces acting on the ball. Depending on the orientations of the seam and the spin axis, a sideways force on a baseball can arise either if there is rough patch on one side of the ball or if there is a smooth patch. A scuff ball with a rough patch on one side is illegal in baseball. The effect of a smooth patch is a surprising new observation.

  1. Biomechanics of Heading a Soccer Ball: Implications for Player Safety

    Directory of Open Access Journals (Sweden)

    Charles F. Babbs

    2001-01-01

    Full Text Available To better understand the risk and safety of heading a soccer ball, the author created a set of simple mathematical models based upon Newton�s second law of motion to describe the physics of heading. These models describe the player, the ball, the flight of the ball before impact, the motion of the head and ball during impact, and the effects of all of these upon the intensity and the duration of acceleration of the head. The calculated head accelerations were compared to those during presumably safe daily activities of jumping, dancing, and head nodding and also were related to established criteria for serious head injury from the motor vehicle crash literature. The results suggest heading is usually safe but occasionally dangerous, depending on key characteristics of both the player and the ball. Safety is greatly improved when players head the ball with greater effective body mass, which is determined by a player�s size, strength, and technique. Smaller youth players, because of their lesser body mass, are more at risk of potentially dangerous headers than are adults, even when using current youth size balls. Lower ball inflation pressure reduces risk of dangerous head accelerations. Lower pressure balls also have greater “touch” and “playability”, measured in terms of contact time and contact area between foot and ball during a kick. Focus on teaching proper technique, the re-design of age-appropriate balls for young players with reduced weight and inflation pressure, and avoidance of head contact with fast, rising balls kicked at close range can substantially reduce risk of subtle brain injury in players who head soccer balls.

  2. Split-ball resonator as a three-dimensional analogue of planar split-rings

    Science.gov (United States)

    Kuznetsov, Arseniy I.; Miroshnichenko, Andrey E.; Hsing Fu, Yuan; Viswanathan, Vignesh; Rahmani, Mohsen; Valuckas, Vytautas; Ying Pan, Zhen; Kivshar, Yuri; Pickard, Daniel S.; Luk'Yanchuk, Boris

    2014-01-01

    Split-ring resonators are basic elements of metamaterials, which can induce a magnetic response in metallic nanosctructures. Tunability of such response up to the visible frequency range is still a challenge. Here we introduce the concept of the split-ball resonator and demonstrate the strong magnetic response in the visible for both gold and silver spherical plasmonic nanoparticles with nanometre scale cuts. We realize this concept experimentally by employing the laser-induced transfer method to produce near-perfect metallic spheres and helium ion beam milling to make cuts with the clean straight sidewalls and nanometre resolution. The magnetic resonance is observed at 600 nm in gold and at 565 nm in silver nanoparticles. This method can be applied to the structuring of arbitrary three-dimensional features on the surface of nanoscale resonators. It provides new ways for engineering hybrid resonant modes and ultra-high near-field enhancement.

  3. Noise exposure in oil mills.

    Science.gov (United States)

    Kumar, G V Prasanna; Dewangan, K N; Sarkar, Amaresh

    2008-04-01

    Noise of machines in various agro-based industries was found to be the major occupational hazard for the workers of industries. The predominant noise sources need to be identified and the causes of high noise need to be studied to undertake the appropriate measures to reduce the noise level in one of the major agro-based industries, oil mills. To identify the predominant noise sources in the workrooms of oil mills. To study the causes of noise in oil mills. To measure the extent of noise exposure of oil mill workers. To examine the response of workers towards noise, so that appropriate measures can be undertaken to minimize the noise exposure. A noise survey was conducted in the three renowned oil mills of north-eastern region of India. Information like output capacity, size of power source, maintenance condition of the machines and workroom configurations of the oil mills was collected by personal observations and enquiry with the owner of the mill. Using a Sound Level Meter (SLM) (Model-824, Larson and Davis, USA), equivalent SPL was measured at operator's ear level in the working zone of the workers near each machine of the mills. In order to study the variation of SPL in the workrooms of the oil mill throughout its operation, equivalent SPL was measured at two appropriate locations of working zone of the workers in each mill. For conducting the noise survey, the guidelines of Canadian Centre for Occupational Health and Safety (CCOHS) were followed. Grid points were marked on the floor of the workroom of the oil mill at a spacing of 1 m x 1 m. SPL at grid points were measured at about 1.5 m above the floor. The direction of the SLM was towards the nearby noisy source. To increase accuracy, two replications were taken at each grid point. All the data were recorded for 30 sec. At the end of the experiment, data were downloaded to a personal computer. With the help of utility software of Larson and Davis, USA, equivalent SPL and noise spectrum at each reading was

  4. Einstein-Yang-Mills from pure Yang-Mills amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Nandan, Dhritiman; Plefka, Jan [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, D-12489 Berlin (Germany); Schlotterer, Oliver [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, D-14476 Potsdam (Germany); Wen, Congkao [I.N.F.N. Sezione di Roma Tor Vergata,Via della Ricerca Scientifica, 00133 Roma (Italy)

    2016-10-14

    We present new relations for scattering amplitudes of color ordered gluons and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary multiplicities and polarizations involving up to three gravitons and up to two color traces are reduced to partial amplitudes of pure Yang-Mills theory. In fact, the double-trace identities apply to Einstein-Yang-Mills extended by a dilaton and a B-field. Our results generalize recent work of Stieberger and Taylor for the single graviton case with a single color trace. As the derivation is made in the dimension-agnostic Cachazo-He-Yuan formalism, our results are valid for external bosons in any number of spacetime dimensions. Moreover, they generalize to the superamplitudes in theories with 16 supercharges.

  5. Vibration analysis of cryocoolers

    Science.gov (United States)

    Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira; Koyama, Tomohiro; Li, Rui

    2004-05-01

    The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas.

  6. Vibration analysis of cryocoolers

    Energy Technology Data Exchange (ETDEWEB)

    Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Koyama, Tomohiro; Rui Li [Sumitomo Heavy Industries Ltd., Tokyo (Japan)

    2004-05-01

    The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas. (Author)

  7. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  8. Characteristics of the mechanical milling on the room temperature ferromagnetism and sensing properties of TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bolokang, A.S., E-mail: Sylvester.Bolokang@transnet.net [Department of Physics, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa); Transnet Engineering, Product Development, Private Bag X 528, Silverton 0127 (South Africa); Cummings, F.R. [Department of Physics, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); Electron Microscope Unit, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); Dhonge, B.P. [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa); Abdallah, H.M.I.; Moyo, T. [School of Chemistry and Physics, Westville Campus, University of KwaZulu-Natal, Private Bag X54001, Durban 4000 (South Africa); Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300 (South Africa); Arendse, C.J.; Muller, T.F.G. [Department of Physics, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); Motaung, D.E., E-mail: dmotaung@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa)

    2015-03-15

    Highlights: • Anatase TiO{sub 2} NPs were milled at different times. • A correlation between defect, magnetization and gas sensing is demonstrated. • Magnetization improved with an increase of a defect-related originating from V{sub O}. • Surface area, pore size and volume improve with milling time. • Milled TiO{sub 2} exhibited enhanced gas-sensing properties to humidity. - Abstract: We report on the correlation between defect-related emissions, the magnetization and sensing of TiO{sub 2} nanoparticles (NPs) prepared by milling method. Surface morphology analyses showed that the size of the TiO{sub 2} NPs decreases with milling time. Raman and XRD studies demonstrated that the structural properties of the TiO{sub 2} transform to orthorhombic structure upon milling. Magnetization improved with an increase of a defect-related band originating from oxygen vacancies (V{sub O}), which can be ascribed to a decrease in the size of the NPs due to the milling time. Moreover, the longer-milled TiO{sub 2} exhibited enhanced gas-sensing properties to humidity in terms of sensor response, with about 12 s response time at room temperature. A combination of photoluminescence, X-ray photoelectron spectroscopy, vibrating sample magnetometer and sensing analyses demonstrated that a direct relation exists between the magnetization, sensing and the relative occupancy of the V{sub O} present on the surface of TiO{sub 2} NPs.

  9. In-Situ Agglomeration and De-agglomeration by Milling of Nano-Engineered Lubricant Particulate Composites for Cold Spray Deposition

    Science.gov (United States)

    Neshastehriz, M.; Smid, I.; Segall, A. E.

    2014-10-01

    Nano-engineered self-lubricating particles comprised of hexagonal-boron-nitride powder (hBN) encapsulated in nickel have been developed for cold spray coating of aluminum components. The nickel encapsulant consists of several nano-sized layers, which are deposited on the hBN particles by electroless plating. In the cold spray deposition, the nickel becomes the matrix in which hBN acts as the lubricant. The coating demonstrated a very promising performance by reducing the coefficient of friction by almost 50% and increasing the wear resistance more than tenfold. The coatings also exhibited higher bond strength, which was directly related to the hardenability of the particles. During the encapsulation process, the hBN particles agglomerate and form large clusters. De-agglomeration has been studied through low- and high-energy ball milling to create more uniform and consistent particle sizes and to improve the cold spray deposition efficiency. The unmilled and milled particles were characterized with Scanning Electron Microscopy, Energy-Dispersive X-Ray Spectroscopy, BET, and hardness tests. It was found that in low-energy ball milling, the clusters were compacted to a noticeable extent. However, the high-energy ball milling resulted in breakup of agglomerations and destroyed the nickel encapsulant.

  10. Effect of Practicing Soccer Juggling With Different Sized Balls Upon Performance, Retention, and Transfer to Ball Reception.

    Science.gov (United States)

    Raastad, Olav; Aune, Tore Kristian; van den Tillaar, Roland

    2016-10-01

    The aim of this study was to investigate if making the skill acquisition phase more difficult or easier would enhance performance in soccer juggling, and if this practice has a positive intertask transfer effect to ball reception performance. Twenty-two adolescent soccer players were tested in juggling a soccer ball and in the control of an approaching ball at a pre, post and retention test. The participants were randomly divided in a small ball size and bigger ball size training group that both trained four times per week for 6 weeks. At the post and retention test both groups enhanced performance in soccer juggling test with no difference between groups and no increase in ball reception performance at these tests. It was concluded that about intra task transfer and retention of soccer juggling skills, it does not matter if you increase (small balls) or decrease the difficulty (larger balls) when using the same amount of practice time within the skill acquisition phase in soccer juggling. In addition that for ball juggling and ball reception (inter task) these two tasks differ too much in afferent information and movement characteristics that no positive transfer between these two skills no positive intertask transfer can be expected.

  11. Magnetohydrodynamics equilibrium of a self-confined elliptical plasma ball

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H. (CCAST (World Laboratory) P. O. Box 8730, Beijing 100080 and Institute of Mechanics, Academia Sinica, Beijing, People' s Republic of China (CN)); Oakes, M.E. (Department of Physics, University of Texas at Austin, Austin, Texas 78712 (USA))

    1991-08-01

    A variational principle is applied to the problem of magnetohydrodynamics (MHD) equilibrium of a self-contained elliptical plasma ball, such as elliptical ball lightning. The principle is appropriate for an approximate solution of partial differential equations with arbitrary boundary shape. The method reduces the partial differential equation to a series of ordinary differential equations and is especially valuable for treating boundaries with nonlinear deformations. The calculations conclude that the pressure distribution and the poloidal current are more uniform in an oblate self-confined plasma ball than that of an elongated plasma ball. The ellipticity of the plasma ball is obviously restricted by its internal pressure, magnetic field, and ambient pressure. Qualitative evidence is presented for the absence of sighting of elongated ball lightning.

  12. Burning molten metallic spheres: One class of ball lightning?

    Science.gov (United States)

    Stephan, Karl D.; Massey, Nathan

    2008-08-01

    Abrahamson and Dinniss [2000. Ball lightning caused by oxidation of nanoparticle networks from normal lightning strikes on soil. Nature 403, 519-521] proposed a theory of ball lighting in which silicon nanoparticles undergo slow oxidation and emit light. Paiva et al. [2007. Production of ball-lightning-like luminous balls by electrical discharges in silicon. Physical Review Letters 98, 048501] reported that an electric arc to silicon produced long-lasting luminous white spheres showing many characteristics of ball lightning. We show experimentally that these consist of burning molten silicon spheres with diameters in the 0.1-1 mm range. The evidence of our experiments leads us to propose that a subset of ball lightning events may consist of macro-scale molten spheres of burning metallic materials likely to be ejected from a conventional lightning strike to earth.

  13. The heads and tails of buoyant autocatalytic balls

    Science.gov (United States)

    Rogers, Michael C.; Morris, Stephen W.

    2012-09-01

    Buoyancy produced by autocatalytic reaction fronts can produce fluid flows that advect the front position, giving rise to interesting feedback between chemical and hydrodynamic effects. In this paper, we numerically investigate the evolution of autocatalytic iodate-arsenous acid reaction fronts initialized in spherical configurations. Deformation of these "autocatalytic balls" is driven by buoyancy produced by the reaction. In our simulations, we have found that depending on the initial ball radius, the reaction front will develop in one of three different ways. In an intermediate range of ball size, the flow can evolve much like an autocatalytic plume: the ball develops a reacting head and tail that is akin to the head and conduit of an autocatalytic plume. In the limit of large autocatalytic balls, however, growth of a reacting tail is suppressed and the resemblance to plumes disappears. Conversely, very small balls of product solution fail to initiate sustained fronts and eventually disappear.

  14. Pengaruh Milling Time Terhadap Pembentukan Intermetalik ɣ-TiAl Sebagai Reinforced Dalam Metal Matrix Composite (MMCs Hasil Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Mohammad Badrus Soleh

    2013-03-01

    Full Text Available Paduan TiAl mempunyai berbagai keunggulan dalam sifat mekanik serta sifat termal. Senyawa intermetalik γ-TiAl mempunyai sifat mekanik dan sifat termal yang sangat baik sehingga sesuai apabila diaplikasikan sebagai penguat pada metal matrix composite (MMCs. Penelitian ini bertujuan untuk mensintesis paduan TiAl sehingga terbentuk  fasa intermetalik γ-TiAl yang homogen. Sintesa dilakukan dengan metode mechanical alloying menggunakan modification horizontal ball mill dengan komposisi paduan Ti-36%wt Al dan variasi milling time 0,10,20 jam dengan kecepatan tetap 350rpm. Hasil milling dikompaksi dan di-annealing pada temperatur 9000C selama 30menit.  Fasa intermetalik γ-TiAl terbentuk setelah proses mechanical alloying 20 jam. Hasil pengujian difraksi sinar X menunjukkan ukuran kristal sebesar 198.92Å pada fasa γ-TiAl, memiliki kekerasan 678,1HV.

  15. Cutting force response in milling of Inconel: analysis by wavelet and Hilbert-Huang Transforms

    Directory of Open Access Journals (Sweden)

    Grzegorz Litak

    Full Text Available We study the milling process of Inconel. By continuously increasing the cutting depth we follow the system response and appearance of oscillations of larger amplitude. The cutting force amplitude and frequency analysis has been done by means of wavelets and Hilbert-Huang transform. We report that in our system the force oscillations are closely related to the rotational motion of the tool and advocate for a regenerative mechanism of chatter vibrations. To identify vibrations amplitudes occurrence in time scale we apply wavelet and Hilbert-Huang transforms.

  16. Ball lightning observation: an objective video-camera analysis report

    OpenAIRE

    Sello, Stefano; Viviani, Paolo; Paganini, Enrico

    2011-01-01

    In this paper we describe a video-camera recording of a (probable) ball lightning event and both the related image and signal analyses for its photometric and dynamical characterization. The results strongly support the BL nature of the recorded luminous ball object and allow the researchers to have an objective and unique video document of a possible BL event for further analyses. Some general evaluations of the obtained results considering the proposed ball lightning models conclude the paper.

  17. Swiss ball to relieve pain of primiparous in active labor

    OpenAIRE

    Gallo, Rubneide Barreto Silva; Santana,Licia Santos; Marcolin,Alessandra Cristina; Quintana,Silvana Maria

    2014-01-01

    BACKGROUND AND OBJECTIVES:The Swiss ball has been widely used in different health sectors. It is considered effective to relieve pain and to help labor evolution, however there are few studies. This study aimed at evaluating the effect of the Swiss ball on pain relief and active labor duration of primiparous.METHODS:This is a randomized and controlled study with 40 primiparous divided in control group and ball group, who carried out pelvic mobility exercises for 30 minutes during active labor...

  18. Galilean Yang-Mills theory

    Energy Technology Data Exchange (ETDEWEB)

    Bagchi, Arjun [Center for Theoretical Physics, Massachusetts Institute of Technology,77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Basu, Rudranil [Saha Institute of Nuclear Physics,Block AF, Sector 1, Bidhannagar, Kolkata 700068 (India); Kakkar, Ashish [Indian Institute of Science Education and Research,Dr Homi Bhabha Road, Pashan. Pune 411008 (India); Mehra, Aditya [Indian Institute of Science Education and Research,Dr Homi Bhabha Road, Pashan. Pune 411008 (India); Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

    2016-04-11

    We investigate the symmetry structure of the non-relativistic limit of Yang-Mills theories. Generalising previous results in the Galilean limit of electrodynamics, we discover that for Yang-Mills theories there are a variety of limits inside the Galilean regime. We first explicitly work with the SU(2) theory and then generalise to SU(N) for all N, systematising our notation and analysis. We discover that the whole family of limits lead to different sectors of Galilean Yang-Mills theories and the equations of motion in each sector exhibit hitherto undiscovered infinite dimensional symmetries, viz. infinite Galilean Conformal symmetries in D=4. These provide the first examples of interacting Galilean Conformal Field Theories (GCFTs) in D>2.

  19. Spherical microwave confinement and ball lightning

    Science.gov (United States)

    Robinson, William Richard

    This dissertation presents the results of research done on unconventional energy technologies from 1995 to 2009. The present civilization depends on an infrastructure that was constructed and is maintained almost entirely using concentrated fuels and ores, both of which will run out. Diffuse renewable energy sources rely on this same infrastructure, and hence face the same limitations. I first examined sonoluminescence directed toward fusion, but demonstrated theoretically that this is impossible. I next studied Low Energy Nuclear Reactions and developed methods for improving results, although these have not been implemented. In 2000, I began Spherical Microwave Confinement (SMC), which confines and heats plasma with microwaves in a spherical chamber. The reactor was designed and built to provide the data needed to investigate the possibility of achieving fusion conditions with microwave confinement. A second objective was to attempt to create ball lightning (BL). The reactor featured 20 magnetrons, which were driven by a capacitor bank and operated in a 0.2 s pulse mode at 2.45 GHz. These provided 20 kW to an icosahedral array of 20 antennas. Video of plasmas led to a redesign of the antennas to provide better coupling of the microwaves to the plasma. A second improvement was a grid at the base of the antennas, which provided corona electrons and an electric field to aid quick formation of plasmas. Although fusion conditions were never achieved and ball lightning not observed, experience gained from operating this basic, affordable system has been incorporated in a more sophisticated reactor design intended for future research. This would use magnets that were originally planned. The cusp geometry of the magnetic fields is suitable for electron cyclotron resonance in the same type of closed surface that in existing reactors has generated high-temperature plasmas. Should ball lightning be created, it could be a practical power source with nearly ideal

  20. Low Compression Tennis Balls and Skill Development

    Science.gov (United States)

    Hammond, John; Smith, Christina

    2006-01-01

    Coaching aims to improve player performance and coaches have a number of coaching methods and strategies they use to enhance this process. If new methods and ideas can be determined to improve player performance they will change coaching practices and processes. This study investigated the effects of using low compression balls (LCBs) during coaching sessions with beginning tennis players. In order to assess the effectiveness of LCBs on skill learning the study employed a quasi-experimental design supported by qualitative and descriptive data. Beginner tennis players took part in coaching sessions, one group using the LCBs while the other group used standard tennis balls. Both groups were administered a skills at the beginning of a series of coaching sessions and again at the end. A statistical investigation of the difference between pre and post-test results was carried out to determine the effect of LCBs on skill learning. Additional qualitative data was obtained through interviews, video capture and the use of performance analysis of typical coaching sessions for each group. The skill test results indicated no difference in skill learning when comparing beginners using the LCBs to those using the standard balls. Coaches reported that the LCBs appeared to have a positive effect on technique development, including aspects of technique that are related to improving power of the shot. Additional benefits were that rallies went on longer and more opportunity for positive reinforcement. In order to provide a more conclusive answer to the effects of LCBs on skill learning and technique development recommendations for future research were established including a more controlled experimental environment and larger sample sizes across a longer period of time. Key Points LCB may aid skill learning in tennis. Qualitative indicators. Statistical evidence not conclusive. Further studies of larger groups recommended. PMID:24357952

  1. LOW COMPRESSION TENNIS BALLS AND SKILL DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    John Hammond

    2006-12-01

    Full Text Available Coaching aims to improve player performance and coaches have a number of coaching methods and strategies they use to enhance this process. If new methods and ideas can be determined to improve player performance they will change coaching practices and processes. This study investigated the effects of using low compression balls (LCBs during coaching sessions with beginning tennis players. In order to assess the effectiveness of LCBs on skill learning the study employed a quasi-experimental design supported by qualitative and descriptive data. Beginner tennis players took part in coaching sessions, one group using the LCBs while the other group used standard tennis balls. Both groups were administered a skills at the beginning of a series of coaching sessions and again at the end. A statistical investigation of the difference between pre and post-test results was carried out to determine the effect of LCBs on skill learning. Additional qualitative data was obtained through interviews, video capture and the use of performance analysis of typical coaching sessions for each group. The skill test results indicated no difference in skill learning when comparing beginners using the LCBs to those using the standard balls. Coaches reported that the LCBs appeared to have a positive effect on technique development, including aspects of technique that are related to improving power of the shot. Additional benefits were that rallies went on longer and more opportunity for positive reinforcement. In order to provide a more conclusive answer to the effects of LCBs on skill learning and technique development recommendations for future research were established including a more controlled experimental environment and larger sample sizes across a longer period of time

  2. Effect of mechanical milling on photoluminescence of gamma-alumina nanoparticles.

    Science.gov (United States)

    Luo, Jinsong; Liu, Shufeng; Wang, Lidan; Fan, Yi; Zhang, Ligong; Zhang, Peiping; An, Linan

    2008-03-01

    The effect of mechanical alloying on the photoluminescence behavior of gamma-Al2O3 nanopowder was studied. Two emission peaks centered at 343 and 378 nm and a broad emission band ranging between 400-600 nm have been observed. It is found that the intensity of the two emission peaks decreases with ball-milling time, while that the broad band remains un-change. These results suggested that the two peaks are resulted from the surface defects that analogs of F+ centers, while the broad band is resulted from impurity.

  3. A proposed experiment on ball lightning model

    Energy Technology Data Exchange (ETDEWEB)

    Ignatovich, Vladimir K., E-mail: v.ignatovi@gmail.com [Frank Laboratory for Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Ignatovich, Filipp V. [1565 Jefferson Rd., 420, Rochester, NY 14623 (United States)

    2011-09-19

    Highlights: → We propose to put a glass sphere inside an excited gas. → Then to put a light ray inside the glass in a whispering gallery mode. → If the light is resonant to gas excitation, it will be amplified at every reflection. → In ms time the light in the glass will be amplified, and will melt the glass. → A liquid shell kept integer by electrostriction forces is the ball lightning model. -- Abstract: We propose an experiment for strong light amplification at multiple total reflections from active gaseous media.

  4. Are Perytons Signatures of Ball Lightning?

    Science.gov (United States)

    Dodin, I. Y.; Fisch, N. J.

    2014-10-01

    The enigmatic downchirped signals, called "perytons," that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning (BL). If BLs act as nonstationary radio frequency cavities, their characteristic emission frequencies and evolution timescales are consistent with peryton observations, and so are general patterns in which BLs are known to occur. Based on this evidence, testable predictions are made that can confirm or rule out a causal connection between perytons and BLs. In either case, how perytons are searched for in observational data may warrant reconsideration because existing procedures may be discarding events that have the same nature as known perytons.

  5. String Balls at the LHC and Beyond

    CERN Document Server

    Dimopoulos, Savas K; Dimopoulos, Savas; Emparan, Roberto

    2002-01-01

    In string theory, black holes have a minimum mass below which they transition into highly excited long and jagged strings --- ``string balls''. These are the stringy progenitors of black holes; because they are lighter, in theories of TeV-gravity, they may be more accessible to the LHC or the VLHC. They share some of the characteristics of black holes, such as large production cross sections. Furthermore, they evaporate thermally at the Hagedorn temperature and give rise to high-multiplicity events containing hard primary photons and charged leptons, which have negligible standard-model background.

  6. Quenching simulation of steel grinding balls

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Hernandez, O.; Reyes, L. A.; Camurri, C.; Carrasco, C.; Garza-Monte-de-Oca, F.; Colas, R.

    2015-07-01

    The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses. (Author)

  7. Two Cases of Hair Balls in Girls

    OpenAIRE

    Vladimir A. Shcherbak; Sergey G. Gaymolenko; Valentina G. Cherdantseva

    2016-01-01

    This article describes two cases of hair balls in girls between aged 2.5 and 12 years. The reason for this quite rare disease may be trichotillomania (compulsive desire to pull out own hair) and trichophagia (compulsive or impulsive desire to pull out, and then to swallow own or someone's hair) typical for Rapunzel syndrome. Initially, the children were enrolled in the Oncology Centre in view of suspected abdominal tumour. After detection of foreign bodies in the stomach, they were transferre...

  8. Promoting ball skills in preschool-age girls.

    Science.gov (United States)

    Veldman, Sanne L C; Palmer, Kara K; Okely, Anthony D; Robinson, Leah E

    2017-01-01

    Evidence supports that girls are less proficient than boys at performing ball skills. This study examined the immediate and long-term effects of a ball skill intervention on preschool-age girls' ball skill performance. Randomized controlled trial. Girls (Mage=47.24±7.38 months) were randomly assigned to a high autonomy, mastery-based 9-week motor skill intervention (the Children's Health Activity Motor Program; CHAMP, 540min; n=38) or a control group (free-play; n=16). Ball skill proficiency was assessed at pretest, posttest, and retention test (after 9 weeks) using the object control subscale of the Test of Gross Motor Development - 2nd Edition. Treatment efficacy was examined using linear mixed models. Two models were fit: one for short-term changes (pretest to posttest) and one for long-term changes (pretest to retention). Linear mixed models revealed a significantly time*treatment interaction for both models. Post hoc analysis confirmed that girls in CHAMP experienced significant gains in ball skills from pretest to posttest (pdifferent from the control group at pretest (p>.05) but had significantly higher ball skills scores at both posttest (pskill intervention (i.e., CHAMP) on improving girls' ball skills both short- and long-term. Findings suggest that early childhood interventions that focus on the development of ball skills in young girls might be an avenue to improve girls' ball skill performance. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  9. [Diagnosis and treatment of fungal ball rhino-sinusitis].

    Science.gov (United States)

    Nie, Jun; Liu, Fenfang; Zhang, Hanwu; Li, Li

    2013-07-01

    To explore the diagnosis and treatment of the fungal ball rhino-sinusitis. The clinical data of 128 cases with the fungal ball rhino-sinusitis in our hospital between September 2005 and January 2012 were retrospectively analyzed. All patients were accepted nasal endoscopic surgery and followed up after surgery. The diagnosis were confirmed by postoperative pathological examination. The sinus of all patients epithelialized after the surgery from fourth to ninth weeks, one case recurred eight months later. Sinus CT scan and nasal endoscopy were very important to the diagnosis of the fungal ball rhino-sinusitis, and nasal endoscopic surgery is the most important treatment method to fungal ball rhino-sinusitis.

  10. Soil Carbon 4 per mille

    Science.gov (United States)

    Minasny, Budiman; van Wesemael, Bas

    2017-04-01

    The '4 per mille Soils for Food Security and Climate' was launched at the COP21 aiming to increase global soil organic matter stocks by 4 per mille (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New Zealand, Chile, South Africa, Australia, Tanzania, Indonesia, Kenya, Nigeria, India, China Taiwan, South Korea, China Mainland, United States of America, France, Canada, Belgium, England & Wales, Ireland, Scotland, and Russia) and asked whether the 4 per mille initiative is feasible. This study highlights region specific efforts and scopes for soil carbon sequestration. Reported soil C sequestration rates generally show that under best management practices, 4 per mille or even higher sequestration rates can be accomplished. High C sequestration rates (up to 10 per mille) can be achieved for soils with low initial SOC stock (topsoil less than 30 t C ha-1), and at the first twenty years after implementation of best management practices. In addition, areas that have reached equilibrium but not at their saturation level will not be able to further increase their sequestration. We found that most studies on SOC sequestration globally only consider topsoil (up to 0.3 m depth), as it is considered to be most affected by management techniques. The 4 per mille initiative was based on a blanket calculation of the whole global soil profile C stock, however the potential to increase SOC is mostly on managed agricultural lands. If we consider 4 per mille on global topsoil of agricultural land, SOC sequestration is about 3.6 Gt C per year, which effectively offset 40% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration buys time over the next ten to twenty years while other effective sequestration and low carbon technologies become

  11. RELATIONSHIP BETWEEN MEDICINE BALL EXPLOSIVE POWER TESTS, THROWING BALL VELOCITY AND JUMP PERFORMANCE IN TEAM HANDBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Mourad Fathloun

    2011-04-01

    Full Text Available In this study, the relationships between medicine ball explosive power tests, jump and handball throwing velocity performance in team handball players were investigated. Explosive test was measured by a medicine ball throw. Specific explosive strength was evaluated by making 3 types of overarm throw: standing position, using an adapted chair (without run-up, T w , a 3-step running throw (T 3-Steps and a jump shot (J S . The jump test (SJ, CMJ and FCMJ were determined using the OptoJump. The medicine ball explosive power test was closely related to T 3-Steps . Significant relationships were observed between medicine ball explosive power tests and (J S and (T w . The Medicine ball explosive power test is also positively related to vertical jump ability represented by Squat Jump (SJ and Countermovement Jump (CMJ. The results suggest an association of the medicine ball explosive power tests to performance in throwing events

  12. Mutual transformation between crystalline phases in silicon after treatment in a planetary mill: HRTEM studies.

    Science.gov (United States)

    Kulnitskiy, Boris; Annenkov, Mikhail; Perezhogin, Igor; Popov, Mikhail; Ovsyannikov, Danila; Blank, Vladimir

    2016-10-01

    High-resolution transmission electron microscopy (HRTEM) studies of silicon after treatment in a planetary mill have been performed. It is shown that along with the initial phase of silicon, Si-I, the sample also contains some high-pressure phases: Si-III (Kasper phase) and Si-IV (lonsdaleite). We studied the orientation relationship between the particles of different phases, finding that there are, in general, two mechanisms of formation of Si-IV: (1) through the stacking faults formation; (2) through the transformation first to the Kasper phase (Si-III), and then from the Kasper phase to Si-IV. Estimations of temperature and pressure conditions in the planetary ball mill made previously are in accordance with the conditions of formation of the above-mentioned phases.

  13. Uranium Mines and Mills Location Database

    Science.gov (United States)

    The Uranium Mines and Mills location database identifies and shows the location of active and inactive uranium mines and mills, as well as mines which principally produced other minerals, but were known to have uranium in the ore.

  14. Model-based Process Monitoring and Control of Micro-milling using Active Magnetic Bearings

    OpenAIRE

    Blom, R.S.

    2011-01-01

    The process of micro-milling is a promising technology for the fabrication of micro-parts with arbitrary 3D features in a wide range of materials. However, as a result of the reduced dimensions, the susceptibility of the process for machine tool errors and vibrations is higher, having adverse effects on accuracy and surface quality of the resulting workpieces. Furthermore, the production time and the efficiency of the process suffer from low material removal rates and excessive tool wear and ...

  15. Integration of micro milling highspeed spindle on a microEDM-milling machine set-up

    DEFF Research Database (Denmark)

    De Grave, Arnaud; Hansen, Hans Nørgaard; Andolfatto, Loic

    2009-01-01

    In order to cope with repositioning errors and to combine the fast removal rate of micro milling with the precision and small feature size achievable with micro EDM milling, a hybrid micro-milling and micro-EDM milling centre was built and tested. The aim was to build an affordable set-up, easy...

  16. Would John Stuart Mill have regulated pornography?

    OpenAIRE

    McGlynn, C.; Ward, I.

    2014-01-01

    John Stuart Mill dominates contemporary pornography debates where he is routinely invoked as an authoritative defence against regulation. This article, by contrast, argues that a broader understanding of Mill's ethical liberalism, his utilitarianism, and his feminism casts doubt over such an assumption. New insights into Mill's approach to sex, sexual activity, and the regulation of prostitution reveal an altogether more nuanced and activist approach. We conclude that John Stuart Mill would a...

  17. Two Cases of Hair Balls in Girls

    Directory of Open Access Journals (Sweden)

    Vladimir A. Shcherbak

    2016-01-01

    Full Text Available This article describes two cases of hair balls in girls between aged 2.5 and 12 years. The reason for this quite rare disease may be trichotillomania (compulsive desire to pull out own hair and trichophagia (compulsive or impulsive desire to pull out, and then to swallow own or someone's hair typical for Rapunzel syndrome. Initially, the children were enrolled in the Oncology Centre in view of suspected abdominal tumour. After detection of foreign bodies in the stomach, they were transferred to the Department of Clean Surgery. The following surgeries were performed: median laparotomy, gastrotomy on the front wall of the stomach, bezoar removal. Hair balls were dense felt-like conglomerates with a strong offensive odour. Bezoar dimensions of the younger girl were 855, the elder one — 20108 cm. Postoperative period was uneventful. The children were discharged in a satisfactory condition to be followed up by a surgeon, paediatrician, and psychiatrist in their community.

  18. Machine Shop. Module 6: Milling. Instructor's Guide.

    Science.gov (United States)

    Walden, Charles H.

    This document consists of materials for a 12-unit course on the following topics: (1) introduction to milling; (2) structure and accessories; (3) safety and maintenance; (4) cutting-tool variables; (5) basic set-up activities; (6) squaring a workpiece; (7) hole-making operations; (8) form milling; (9) machining keyways; (10) milling angular…

  19. Wear of micro end mills

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2005-01-01

    part. For this investigation 200 microns end mills are considered. Visual inspection of the micro tools requires high magnification and depth of focus. 3D reconstruction based on scanning electron microscope (SEM) images and stereo-pair technique is foreseen as a possible method for quantification...

  20. Soil carbon 4 per mille

    NARCIS (Netherlands)

    Mulder, V.L.

    2017-01-01

    The ‘4 per mille Soils for Food Security and Climate’ was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil

  1. The automatic lumber planing mill

    Science.gov (United States)

    Peter Koch

    1957-01-01

    It is probable that a truly automatic planning operation could be devised if some of the variables commonly present in the mill-run lumber were eliminated and the remaining variables kept under close control. This paper will deal with the more general situation faced by mostl umber manufacturing plants. In other words, it will be assumed that the incoming lumber has...

  2. J. S. Mill on Education

    Science.gov (United States)

    Ryan, Alan

    2011-01-01

    Mill may be said either to have written rather little on education or to have written a very great deal. He himself distinguished between a "narrow" and a "wider" sense of education, the former limited to what happens in formal educational settings, the latter embracing all the influences that make us who and what we are. He wrote rather little on…

  3. Launch Creativity with Ping-Pong Ball Challenge

    Science.gov (United States)

    Kornoelje, Joanne; Roman, Harry T.

    2011-01-01

    Educators at Thomas A. Edison Middle School have worked together to bring invention information and activities to life. One activity in particular, Ping-Pong Ball Invention Challenge, has proven a great success. The Ping-Pong Ball Invention Challenge was inspired by the basic rules for PBS's "Design Squad"'s "Pop Fly" activity. In this article,…

  4. The Net Physiological Cost of Dribbling a Soccer Ball.

    Science.gov (United States)

    Reilly, Thomas; Ball, David

    1984-01-01

    To establish the net energy cost of dribbling a soccer ball, eight males ran on a treadmill while dribbling a ball against a rebound box. Oxygen uptake, perceived exertion, and blood lactate levels were measured and compared with results from subjects running without dribbling. Results are discussed. (Author/DF)

  5. Learning to See the Ball Using the Alexander Technique

    Science.gov (United States)

    Gosselin, Gaynelle

    2011-01-01

    This article begins with a personal anecdote from the author, for whom childhood P.E. classes were exercises in frustration and humiliation largely because she could not master the coordination needed to catch, throw, or hit a ball. She could not keep her eye on the ball despite well-meaning instruction from coaches, friends, and family members.…

  6. Physical Activity Benefits Creativity: Squeezing a Ball for Enhancing Creativity

    Science.gov (United States)

    Kim, JongHan

    2015-01-01

    Studies in embodied cognition show that physical sensations, such as touch and movement, influence cognitive processes. Two studies were conducted to test whether squeezing a soft versus a hard ball facilitates different types of creativity. Squeezing a malleable ball would increase divergent creativity by catalyzing multiple or alternative ideas,…

  7. Exact solutions, energy, and charge of stable Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Marques, M.A. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil)

    2016-05-15

    In this work we deal with nontopological solutions of the Q-ball type in two spacetime dimensions. We study models of current interest, described by a Higgs-like and other, similar potentials which unveil the presence of exact solutions. We use the analytic results to investigate how to control the energy and charge to make the Q-balls stable. (orig.)

  8. How Magnus Bends the Flying Ball - Experimenting and Modeling

    Science.gov (United States)

    Timková, V.; Ješková, Z.

    2017-02-01

    Students are well aware of the effect of the deflection of sports balls when they have been given a spin. A volleyball, tennis, or table tennis ball served with topspin results in an additional downward force that makes the ball difficult to catch and return. In soccer, the effect of sidespin causes the ball to curve unexpectedly sideways, resulting in a so-called banana kick that can confuse the goalkeeper. These surprising effects attract students' attention such that the motion of sports balls can be used to capture the interest of students towards the physics behind it. However, to study and analyze the motion of a real ball kicked in a playfield is not an easy task. Instead of the large-scale full-size sports ball motion, there can be designed and studied simpler experiments that can be carried out in the classroom. Moreover, digital technologies that are available at schools enable students to collect data from the experiment easily in a reasonable time. The mathematical model based on the analysis of forces acting on the ball flying in the air can be used to simulate the motion in order to understand the basic physical principles of the motion so that the best correspondence may be found.

  9. Strongly exposed points in the ball of the Bergman space.

    NARCIS (Netherlands)

    Beneker, P.R.; Wiegerinck, J.J.O.O.

    2005-01-01

    Abstract. We investigate which boundary points in the closed unit ball of the Bergman space A1 are strongly exposed. This requires study of the Bergman projection and its kernel, the annihilator of Bergman space. We show that all polynomials in the boundary of the unit ball are strongly exposed.

  10. Comparative analysis of niobium and vanadium carbide efficiency in the high energy mechanical milling of aluminum bronze alloy

    Directory of Open Access Journals (Sweden)

    Alexandre Nogueira Ottoboni Dias

    Full Text Available Abstract This study aims to analyze the efficiency of niobium and vanadium carbides in the high energy mechanical milling of aluminum bronze alloy. Two series of experiments were made following the same steps for both niobium carbide (NbC and vanadium carbide (VC additions: 30 g of chips were weighed and placed in a stainless steel jar with 3 % of carbide and 1 % of stearic acid for a mass/sphere relationship of 1:10. The milling was realized using a planetary ball mill for 10, 30 and 50 hours in an inert argon atmosphere at 300 rpm. Results shown in laser diffraction indicate a great reduction in the particle sizes of powders when VC is used. For 30 hours milling, D50 values ranged from 1580 µm with NbC to 182.3 µm with VC addition. The D50 values ranged from 251.5 µm with NbC to 52.26 µm with VC addition, for 50 hours milling. The scanning electron microscopy showed that in 10 hours of milling, the energy was not sufficient to achieve the shear of chips in both cases. For 30 hours, it's possible to observe particles with sizes between 100 µm and 800 µm with NbC addition while for the same milling time, with VC it's possible to see particles with different sizes, but with many shapes of fine particulates. For 50 hours milling, particles achieved the smaller sizes between 50 and 200 µm with NbC and ranging from 5 until 50 µm with VC addition.

  11. Une balle blanche dans un roman noir

    Directory of Open Access Journals (Sweden)

    Sophie Vallas

    2012-03-01

    Full Text Available En 1982, Paul Auster fit paraître, sous le pseudonyme de Paul Benjamin, un roman noir intitulé Squeeze Play. Ce roman présente la particularité d’appartenir également au genre du baseball novel, l’intrigue se déroulant en partie dans le monde du base-ball et sa résolution intervenant grâce à une manœuvre rare et spectaculaire (un double suicide squeeze qui éclaire l’enquête sous un jour nouveau. Cet article se propose d’analyser la place du base-ball dans Squeeze Play : élément essentiel de la structuration du roman, le base-ball permet également à Auster d’étudier le mythe du héros américain déchu dans une société dont toutes les dimensions (sportive, politique, privée sont gangrenées par la corruption et la perversion. La relation particulière qu’Auster tisse entre roman noir et baseball novel est également étudiée.In 1982 Paul Auster published a roman noir entitled Squeeze Play under the pseudonym of Paul Benjamin. The novel is also a “baseball novel”: its plot essentially deals with a baseball New York team and its former, fallen star, and the final resolution of the mystery intervenes thanks to a revelation brought by a baseball game in which a rather rare and spectacular maneuver (the double suicide squeeze is used by one of the teams to turn the tables and win the game. This paper analyzes the place of baseball in Squeeze Play: it first appears as an essential element in the very structure of the plot, but it is also, for Auster, a way of questioning the myth of the hero in an American society whose main aspects (sports, politics, private life are eaten up by corruption and perversion. The links Auster establishes between roman noir and baseball novel are also dealt with.

  12. analysis of gear milling at vari gear milling at various gear milling

    African Journals Online (AJOL)

    eobe

    feedrates for cutting a tooth ing a tooth ing a tooth of a spur gear. Thus, as of a spur gear. Thus, as. The model will serve as a useful tool in prepar. Keywords: Cutting speed, feedrate, time. 1. INTRODUCTION. INTRODUCTION. INTRODUCTION. In milling, a multi-toothed cutter, rotating at a fi position on the machine, shapes ...

  13. Psychophysics: how fielders arrive in time to catch the ball.

    Science.gov (United States)

    McLeod, Peter; Reed, Nick; Dienes, Zoltan

    2003-11-20

    Tracking an object moving in three dimensions, whether as an insect pursuing a mate on the wing or as a batsman aiming to hit an approaching ball, provides the spatial and temporal information needed to intercept it. Here we show how fielders use such tracking signals to arrive at the right place in time to catch a ball - they run so that their angle of gaze elevation to the ball increases at a decreasing rate while their horizontal gaze angle to the ball increases at a constant rate (unless the distance to be run is small). Allowing the horizontal angle to increase minimizes the acceleration that the fielder must achieve to reach the interception point at the same time as the ball.

  14. Model Indepedent Vibration Control

    OpenAIRE

    Yuan, Jing

    2010-01-01

    A NMIFC system is proposed for broadband vibration control. It has two important features. Feature F1 is that the NMIFC is stable without introducing any invasive effects, such as probing signals or controller perturbations, into the vibration system; feature F2 is

  15. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration...

  16. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 2nd edition of this textbook on linear stochastic vibration...

  17. Hydroelastic Vibrations of Ships

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Folsø, Rasmus

    2002-01-01

    A formula for the necessary hull girder bending stiffness required to avoid serious springing vibrations is derived. The expression takes into account the zero crossing period of the waves, the ship speed and main dimensions. For whipping vibrations the probability of exceedance for the combined...

  18. Gearbox vibration diagnostic analyzer

    Science.gov (United States)

    1992-01-01

    This report describes the Gearbox Vibration Diagnostic Analyzer installed in the NASA Lewis Research Center's 500 HP Helicopter Transmission Test Stand to monitor gearbox testing. The vibration of the gearbox is analyzed using diagnostic algorithms to calculate a parameter indicating damaged components.

  19. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    Lalanne, Christian

    2014-01-01

    Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

  20. Accuracy and Reliability of a New Tennis Ball Machine

    Directory of Open Access Journals (Sweden)

    Cyril Brechbuhl, Grégoire Millet, Laurent Schmitt

    2016-06-01

    Full Text Available The aim was to evaluate the reliability of a newly-developed ball machine named 'Hightof', on the field and to assess its accuracy. The experiment was conducted in the collaboration of the 'Hawk-Eye' technology. The accuracy and reliability of this ball machine were assessed during an incremental test, with 1 min of exercise and 30 sec of recovery, where the frequency of the balls increased from 10 to 30 balls·min-1. The initial frequency was 10 and increased by 2 until 22, then by 1 until 30 balls·min-1. The reference points for the impact were 8.39m from the net and 2.70m from lateral line for the right side and 2.83m for the left side. The precision of the machine was similar on the right and left sides (0.63 ± 0.39 vs 0.63 ± 0.34 m. The distances to the reference point were 0.52 ± 0.42, 0.26 ± 0.19, 0.52 ± 0.37, 0.28 ± 0.19 m for the Y-right, X-right, Y-left and X-left impacts. The precision was constant and did not increase with the intensity. (e.g ball frequency. The ball velocity was 86.3 ± 1.5 and 86.5 ± 1.3 km·h-1 for the right and the left side, respectively. The coefficient of variation for the velocity ranged between 1 and 2% in all stages (ball velocity ranging from 10 to 30 balls·min-1. Conclusion: both the accuracy and the reliability of this new ball machine appear satisfying enough for field testing and training.